Representational and Authentic: Sustainable Heritage Message through Architectural Experience in the Case of Bernard Tschumi’s Acropolis Museum, Athens

: Bernard Tschumi’s Acropolis Museum represents the historical heritage value entailing the traces of the time with the combinations of diverse elements. The experience of the value of immanent heritage is a special process engaging both body and mind. This paper ranges from the planning of the museum to an examination of the purpose of the design concept and its close relationship with the surrounding urban context. The design concept of the coexistence of the excava tion site and the new museum is analyzed in cross-sectional and structural terms. The way the message of the past of the Acropolis’s heritage meets with the present architecture of today’s museum with the keyword experience is also analyzed. Overall, it focuses on the delicate process of coordination where the old and new meet. In this respect, the Acropolis Museum is an example of recreating authentic heritage.


Introduction
Museums that exhibit a historical heritage are architecture that house time. This is the process of constructing new structures while maintaining traces of heritage and balancing the old and the new. In particular, museums that use historical sites optimally preserve the structure of the ruins, completing the museum by placing a new structure on top of them. This process entails a continuous process of integrating the two values of preservation and transformation. Designing a space for a new program while maintaining the outline and frame of a given historic site as much as possible is both intricate [1] and unique [2] in every case. Therefore, a detailed observation and analysis on the way the old and the new meet is required as well as how the sensations experienced at that encounter point can provide [3] an authentic message on the value of the heritage.
The Acropolis Museum is a contemporary exhibition facility built on the remnants of the ancient city below ( Figure 1). As one of the most emblematic museums and sensitive cultural projects [1] (pp. [23][24][25][26][27][28][29][30][31], this museum establishes an architectural and cultural dialogue between old and new elements. To be strong and convincing, the concept has to be simple. The museum consists of the stacking and rotation of two gallery prisms that contextualize vision and light [4] (pp. 63-85). This research focuses on how the specific architectural situation of the stack, the gaze, and the effect of light [5,6] relate to the values of the exhibited heritage and create a viable synthesis.  [7], (b) concept sketches [8].
The Acropolis Museum has a unique architectural value in terms of spatially representing everyday life in ancient Greece. It shows a new pattern in the way modern people experience and view historical heritage, and at the same time, this is unique evidence of the daily lives of the individuals who lived in the shadow of the Acropolis [4] (p. 29). By providing a variety of spatial experiences within the old structure, it further strengthens the value and authenticity of the heritage. By doing so, it simultaneously allows for the unexpected and promotes a new sense of the whole. The museum brings together concept and experience [3] and succeeds in becoming part of the city on both physical and mental levels [4] (p. 56). The museum is a connection between the past and the present, and as the value of experience [9] is added to it, it expands into a coherent historical message. This paper architecturally analyzes the authentic value of the heritage that is represented through the experience of space. Bernard Tschumi's Acropolis Museum is one of the most emblematic works, showing a balance of both preservation and representation. As a case of experiencing [10] accumulation of time [11] and gradual change [12], this research is focusing on analyzing the specific architectural strategy [9] of this museum, which will give a sustainable message to other global museum cases. The architectural experience that penetrates through the part that preserves the originality of the ancient ruins as it is and the new part that has been reinterpreted enables a sustainable connection between the past and the present, more actively showing the authenticity of the value of the heritage. This is a positive example of architectural sustainability.

Methodology and Scope
The Acropolis Museum has a quite extraordinary architectural context in that it is placed on top of original ruins while preserving the historic structure. The Kolumba Museum in Germany (Figure 2a [6,13,14] that they reveal the layering of time as it is. In all these cases, the sites are themselves historical heritage. The two keywords, conservation and representation, are fundamental issues that museums deal with. However, the spectrum of the proportions of conservation and reproduction of each is broad. Each architect has taken a particular design attitude toward the way the two engage with each other. In the international competition, Tschumi's design was unanimously selected by the judges, and the distinctiveness of the Acropolis Museum begins with the design concept. It is a building that, quite literally, could not have been constructed anywhere else in the world and today, the museum and excavation have been combined into a unique, pioneering exhibition ensemble [16]. The encounter between the excavation site and the new museum was a concept tailored to archaeological excavations, and itself has value as a unique heritage [17]. Excavations began in 1997 on the newly selected site for the museum. Initially, the excavated remains were removed, and construction work proceeded with the existing design guidelines. However, the findings of the excavation for the new museum proved significant, the architectural drawings were modified, and the antiquities were preserved. The proposal placed the museum building on a grid system of foundation columns, with large expanses of glass flooring above the excavation enabling panoramic views onto the historical environment below. Generous interior spaces with a simple layout allow a comfortable display of the exhibits and located the Parthenon sculptures in an almost open-air space [4] (p. 100). This is a combination of the unique context of the land and the heritage values of the exhibits. This particularity is also revealed in Tschumi's collage submitted for the Acropolis Museum design competition.
Another feature is the intimate relationship between this museum and the nearby Parthenon. The Acropolis 400 m away and the Parthenon above it are both geographically and conceptually the fundamental references for the new museum. The size of the museum, the structural modules, the direction of the opening, and the width and circumference of the internal exhibition hall and the corridors surrounding it are all inspiring. In this contextual aspect, a detailed analysis is required on how the architecture, the remains within it, and the Parthenon beyond it are related and intertwined with experience.
The process of the approach to analyze the specificity of the Acropolis Museum is shown in Figure 3. As a component [18] of the architectural experience [19], the architect's intention [20], the architectural drawings, and the process of using the space are examined. To approach these elements individually, we first analyze the architect's interviews, essays, diagrams, and sketches. This is connected to the meaning of analyzing the architectural experience that Norberg-Schulz emphasized. As Norberg-Schulz emphasized the meaning of analyzing the architectural experience [21], an account of the experience of architecture treats the question of how architecture, in the widest sense of the word, is "used" [22]. Figure 3 shows the logical flow from Section 2 to the conclusion. Section 2 reveals the importance of the uniqueness of the Acropolis Museum from its design concept to its close meaning with the adjacent Parthenon. Subsequently, Section 3 analyzes the intensity of representation of this museum sequentially. Section 4 analyzes the real value of heritage through representation in detail by dividing it into types that are experienced in various contexts. Through this, it is possible to confirm the delicate relationship between the method of representation and the value of the heritage.

Result: The Representation According to the Degree of Activity
This section approaches the exhibits of the Acropolis in terms of representation. The first type deals with exhibited objects based on the independent value of the heritage of the exhibit itself. Because it focuses on a single value, viewers see the original remains as they are. The second is the representation of the relationship between units. This is not a representation of the independent ruins as they are, but a method of implicitly reproducing the height, density, and community patterns where the ruins are located. The third is spatial and architectural representation, which more comprehensively reproduces the structural atmosphere, lighting mood, viewing patterns, and the way people inhabited the site in its original form. This can be seen as the most active method of representation in terms of reproducing the context and situation of the past.

Direct Conservation to Convey the Independent Heritage Value
Direct conservation is a method intended to reveal the original quality of the site by focusing on the individual properties of the ruins. The site is directly displayed as it is, without any extra additions or corrections. The texture of the surface retains traces of wear and weathering, as well as the flow of time that has passed since the time when the structures were intact. This is a case that has added value as an exhibit in that it holds both the originality of the work and the traces of time.
As shown in Figure 4a-d below, there are some disappearances and transformations such as sculpture and stone decorations from the Greek period, but the original state is preserved and exhibited as is. It shows individual and unique value without reinforcement for the lost parts. Freestanding exhibits are installed on bases made out of white Helicon marble similar to the floor surface so that the bases are discreet and do not distract the visitor [4] (p. 42). Through this, it is possible to focus on the appreciation of the artifacts as independent entities without visual interference from surrounding materials.

Relational Representation with Allusions and Implications
Relational representation is not direct representation but is instead based on the relationship between two or more artifacts. This is a case of reproducing the properties of the past in a way that implicitly or explicitly stimulates the imagination. Sculptures that were originally placed in a high position [18] are shown elevated, and parts that were low are shown low. In addition, parts that have been lost with the passage of time may be substituted with similar materials, or a sense of contrast may be emphasized by the use of heterogeneous materials ( Figure 4e). Various materials such as glass, stucco, and metal ( Figure 4h) are used to stimulate the viewer's imagination. In the case of the surrounding ruins, an enclosure is secured to form a relevant group cluster. In addition, the high-density ruins [23] reproduce the density portions, while the loose group shows the inherent low density of other areas. By implicitly formulating the cluster pattern and the relationship between each other, it stimulates the viewer to imagine the sum of the whole in its original era.
Relational representation goes beyond the representation of a single exhibit and in addition reproduces other aspects and its context. This could be, for example, the height, the background, and the composition of the group. It is significant in that it expands to a greater value based on visual objects or imagination that complement the limiting properties of the remaining ruins.
In the case of the Acropolis Museum, the diversity of materials also plays a large role in stimulating the imagination. Sometimes the original appearance is suggested by a white stucco material similar to the color of the ruins (Figure 4g). The relatively minimal approach shows only the relationship between height and height, and sometimes a substitute sculpture is inserted, allowing more freedom of imagination. By leaving space for imagination, it helps to prevent thinking patterns from being fixed. The difference in color between the warm patina of the originals and the neutral surface of the white casts ensures the immediate recognition of the difference between an original and a copy by the viewer. On the other hand, the arrangement of restored pieces as they would have originally appeared enables a better understanding of the monument, while simultaneously presenting the real issue underlying the divided Parthenon sculptures in an objective manner [4] (p. 38).
In terms of material, the substance of the walls and columns, which are the background of the exhibition, takes the primary consideration. This allows delicately coordinated exhibits to convey a complete historical message. The choice of concrete walls and columns as the background for statuary requires technical precision: the concrete has to be as smooth as possible but with a soft, lightly sand-blasted texture that would scatter rather than directly reflect light [24]. Similarly, so as not to distract from the art, but instead focus the viewer's attention, the marble bases for the statues blend with the local Greek marble used for flooring throughout the museum [4] (p. 85). Due to this delicate combination, the allusions and implications of the exhibits are reinforced.

Contextual Representation of an Architectural Situation in Space
While direct representation focuses on morphological [25] group relations, contextual representation depends more on spatial and architectural qualities. It recreates or preserves the environment, lighting directions, and the way people experienced the site in the original period. This can be seen as the most active type of representation in terms of reproducing the context and situation of the past. For example, the natural light entering through the gallery's large windows and skylights creates a sense of open-air space that recalls the external setting of the Acropolis sanctuary where the sculptures were originally erected [16] (p. 93). This architectural perspective [26] therefore gives a sense of authenticity.
The first representation of the architectural context begins with the slope design in the middle of the museum. The first gallery of the museum contains archaeological finds from the surrounding slopes of the Acropolis. The slopes, an inseparable part of the rock's topography and history, hosted small and large sanctuaries, places of ancient and more recent cults, venues for public entertainment, and a few private residences in their lower areas. The ascending glass ramp also alludes to the route that ancient visitors themselves followed [16] (p. 35).
The second architectural context is the representation that induces the flow of movement by using the architectural enclosure. By seeing the ruins that were gathered in clusters in the original way, visitors can experience a sense of the inner layout. In addition, outside of the compound, visitors walk around the perimeter, similarly drawing out the movements experienced in ancient ruins. For example, the Caryatids ( Figure 5) are mounted in the same formation as when installed on the ancient building. The Erechtheum friezes are secured to a gray marble backdrop and divided into two groups depending on their scale and original position on the temple [4] (p. 42). Caryatids, arranged according to the original group, delineate the boundary in the temple, showing the outline of the temple from the outside and suggesting the feeling of being surrounded by the original structure on the inside. Adjacent, on a special balcony visible from many vantage points, one can have a firsthand look at the female statues [16] (p. 241). Such a representation of enclosing sense is found in the display method of various relics of the Acropolis Museum.
Let us now analyze the specific architectural representations distributed in the topfloor Parthenon Gallery. First, the frieze and pediment sculptures follow the geometry of the Parthenon itself (Figure 6a-c). The gallery itself [27] is placed parallel or to the ancient temple with a reproduction of the frieze organized around an indoor court to recreate the orientation of its original setting. Because all sides retain their original orientation, they are lit by the same natural light and receive the same shadows (Figure 6d) in an installation that approximates its antique predecessor [4] (p. 62). The light coming down from the upper part and the side reveals the shadows unique to the Parthenon.  The relief blocks of the Parthenon's frieze have been embedded on the external walls of the core (Figure 6c,e) and are displayed for the first time in the same continuous sequence (Figure 6c) they had on the original monument but placed at a lower height to provide better viewing for visitors. The metopes are suspended in pairs between each of the gallery's steel columns, which are the same in number as the marble columns of the Parthenon's outer colonnade [16] (p. 187). In other words, the placement of the pediment, metope, and frieze imply the architectural framework of the Parthenon and are reproduced in the most accessible layout. It is experienced and remembered in a more direct and impactful way by adjusting it to the human scale. In the same way as the crossing the beams of the frieze, we also cross beneath the beams (Figure 6e,f) and look at the frieze in the exhibition space today. In addition, the light that flows between the arrays was also introduced to the actual field of the Acropolis, and a skylight (Figure 6c,d) with a deep sectional thickness was designed for the ceiling. In this way the frieze is not obscured, the angled natural light infiltrates unimpeded between the columns, and simultaneous views of the sculptures in the museum and the building on the sacred rock are assured [4] (p. 38). The integration and the experience of the space that has been concretely reproduced and delivers a nearly authentic sense of the historical heritage.

Discussion: Authentic Heritage Value with the Architectural Experience
This section analyzes how the elements described in Section 3 are connected and stacked, explaining the overall flow of this methodology with the keyword of experience. In Section 4.1, starting from the entrance to the museum space, we examine the sequential flow and sequence of processes to experience the architecture. In Section 4.2, the structure of overlapping, reversal, and penetration of space inserted into the flow of the experience are analyzed three-dimensionally.
Essential to the unique process of space in the museum is the moment when the threshold between visitors and exhibits in the way of is demolished to allow them to appreciate and experience the historical heritage. The movement of art and people and the pillars that guide them intermingle in the middle of the museum space. In order to view the space, one has to walk along it. As in antiquity, movement becomes an indispensable part of the experience [4] (p. 62). In other words, the analysis of experiences in the museum is a work that approaches the process of presenting the value of the past [29]. Through this, the authentic heritage value [30] inherent in the Acropolis Museum can be grasped in more detail and depth.  The museum consists of five levels ( Figure 8). The lowest ground level (Level 1) is the museum's lower part where the archaeological excavation is exhibited. The following is the sloping ramp at the ground floor (level 0), showing exhibits from the slopes of the Acropolis. Next is the first floor (Level 1), divided into two sections by the core part of the building. Above it is the second floor (Level 2), which is used as a restaurant and shop.

Narrative Experience Based on the Architectural Sequence
The last third floor (Level 3) is the Parthenon Gallery, which displays the architectural sculptures from the Parthenon temple. The key concept for viewing this four-stacked architecture is the narrative of time. After entering the lobby through the entrance on the ground floor, full viewing begins at the gallery of the Acropolis Slopes. When the visitor goes up the stairs at the end of the ramp and reaches the first floor, they will see the Archaic Gallery on the right. Continuing to the right and using the escalator in the center to climb two floors in a row, they will arrive at the Parthenon Gallery on the top floor. The entire third floor is devoted to the Parthenon galleries and the architectural scale of the temple can be measured by the outline of the central core. After experiencing the 360-degree view, visitors take the escalator at the point where they first ascended, and the second half flow begins again. After going down two floors and arriving at the first floor, they will see the Post-Parthenon Gallery and the Roman Period Gallery, which show exhibits from the 5th century BC to the 5th century AD. After that, the tour ends through the Acropolis Slopes. Circulation within the museum is organized in the form of a spiral rising vertically from bottom to top and it can be described as an architectural promenade that follows a chronological order [4] (p. 63). This allows the public to have a full appreciation not only of the classical Acropolis but also of the Archaic Period and to follow the development of ancient Athens from an aristocratic state to a tyrannical regime and, finally, to the first democratic system of government in the world [4] (p. 8). This narrative flow of movement allows visitors to experience the message of the museum itself. Walking and observing becomes an act [32] that penetrates the flow of time. The architecture itself is integrated with the heritage to create a chronological spatial experience.

Stimulating Experience to Provide a Viable Heritage Message
The architectural situation of the Acropolis Museum stimulates the visitors' memories, gazes, and movements. This stimulus ultimately connects the experiences of visitors to the museum with the remains of the Acropolis Hill. It expands the experience with the temporal [33] and spatial settings of the time the ruins were created. In Section 4.2, the material characteristics, structural characteristics, and usage characteristics of the museum are sequentially analyzed. By fine-tuning the use of glass, the introduction of gaps, the control of the structure, and the allowable range of movement, it simultaneously allows for the unexpected and promotes a new sense of the coherent whole. The museum brings together concept and experience and succeeds in becoming part of the city on both the physical and the mental levels [4] (p. 56).
The first stimulus conveys a visual message through a transparent material [34]. It goes beyond the visual connection through glass and creates vertical integration through cognitive [35] penetration. Light coming down from the atrium of the Parthenon gallery on the top floor penetrates the glass floor (Figure 9b,c), passes through the Archaic gallery, then the glass panel on the ground floor, and ultimately connects to the archaeological remains under it. This visual connection enables two-way communication from top to bottom and from bottom to top (Figure 9a-d). This psychologically penetrates the ancient heritage and the present experience of viewing the museum, which further interconnects the different spaces of the Museum, establishing vertical unity [4] (p. 63), thereby sustaining the message of the heritage in a contemporary way.
The second stimulus induces [17] movement through the structure. The Acropolis Museum does not divide the space into partitions and walls as is the case in many other museums. By dividing the space using columns rather than partitions, it allows a more casual arrangement. For example, in the Archaic Gallery on the second floor, 29 concrete columns with a height of 8 m are scattered, and ancient relics mixed with these columns form a sense of neighborhood, allowing visitors willing to move around them. This circumambulatory walk becomes a special experience (Figure 9g) that connects the past and the present, which unites the structure of the ruins, visitors, and the modern museum. Each period is integrated in the Archaic Gallery, allowing the present meaning of the past heritage to be eloquently represented. In addition, by not only using columns but also inserting bridges and decks (Figure 9h), visitors are able to traverse certain places and turn their bodies, leading to a variety of specific actions with structures. In particular, the huge structures of the piloti (Figure 9f), which must be passed when entering the museum entrance, provide a wide view through the upper and lower parts of the piloti and generating another sense of unity. Visitors can gain a sense of the environment of the excavation from the views available through the huge opening at the Museum entrance looking down onto the key roadways through the ancient neighborhood, its buildings from late antiquity, two baths, and a house with an andron dating from the classical period [4] (p. 31). The gesture of the structure determines the extent of the visitor's experience. The pillars induce wonderment, the bridge crossing invites movement, the protrusion of the deck causes the visitor to look down, and the huge opening allows them to see and recognize the integration of the multiple eras. Third, regular patterns generate visual order. By matching the linear louvers repeating on the elevation, the pattern of windows, the grid of dots on the wall, and the texture [26] of the concrete wall, a strong homogeneity is created inside and outside the museum. For example, the visual pattern displayed by the openings in the facade creates a strong regularity. Vertical louvers on the first and second floors completely block the line of sight from the cluttered streets and allow a restricted [36] view that is open only toward the Weiler building and the city (Figure 10b,c). This increases the degree of concentration on the exhibition activities inside the museum and presents only a selected open view in a directional way, providing the rhythmical mood on the viewing pattern. The silk-screen dot gradient employed on the glass of the Parthenon and Archaic Gallery is among the minimalist details used throughout the museum. This dot pattern (Figure 10d) is echoed elsewhere: a similar point grid is etched into the nonslip surface of the transparent glass ramp overlooking the excavations, and the visual motif is subtly inflected in and on the concrete cores (Figure 10e) on either side of the atrium, where round holes serve as acoustic "sponges" to minimize the reflection of sound by the hard surfaces [4] (p. 85). The regular patterns have a multilayered effect on the visitor's experience, giving a sense of rhythm to the viewing and reinforcing the sense of unity of the space by integrating vertical and horizontal lines. In addition, it provides convenience and concentration to the viewing behavior by preventing slippery and sound resonating in the ramp space. Fourth, at the Acropolis Museum, visitors are given the option of autonomy, allowing them to make their spatial experience a personal and individual memory [37]. This makes the way of experiencing and remembering the heritage also unique to the individual, further imprinting the value of the heritage. For example, the hurried visitor can view key exhibits by quickly traversing the spacious gallery, while the visitor who wishes to become more familiar with the archaic world will easily identify the central exhibits and their related thematic groups. For the first time, visitors with the desire to have 360-degree views of objects can do so. With the benefit of changing natural light, they can discover the delicate surface variations of the statues and choose the most interesting vantage points from which to observe the works of art. In this way, viewing the exhibition and its objects becomes an entirely personal experience. Visitors can take the stairs, escalator, or elevators to reach the next level of the museum [4] (p. 65). In other words, they can autonomously select the means of movement (Figure 10g,h), its direction, and their viewpoints (Figure 10i). This autonomy is accumulated, and the brightness of the viewing, the viewing angle and the speed of the movement process are personally selected. This choice and participation make the experience in the space quite personal, allowing one to experience and remember the heritage in its own way. Section 4 focuses on the passage of time and the strategy of the intervening architectural device. The flow (Figure 11) of narrative movement considering the passage of time allowed the museum to physically penetrate the message as a historical heritage. The actions of walking and observing behaviors are elements that constitute a part of the narrative. This narrative message is revealed in more detail in Section 4.2. Section 4.2 subdivided the stimuli inserted between the overall experience of viewing. In terms of stimulation through materials, insertion of structures, usage of patterns, and permission of autonomous choice, it was confirmed that the Acropolis Museum is a museum that delivers a holistic message of experience that is distinct from other historical museums. It is a project that has created an independent value that goes beyond uniformity and universality.

Conclusions
In terms of history, a variety of modes exist, such as oral and written history. The Acropolis Museum is an architecture that provides a history of experience. This is a work in which memory and history are spatialized [34] (p. 25) in the architectural experience. In the Acropolis Museum, the experience of the value of the immanent heritage is a special process engaging both body and mind. The scope of this paper has ranged from the planning of the museum, an international competition, to an examination of the purpose of the design concept and its close relationship with the surrounding urban context. The design concept of the coexistence of the excavation site and the new museum was analyzed in cross-sectional and structural terms. Through this, I approached the way the message of the past of the Acropolis's heritage meets with the present architecture of today's museum with the keyword experience, focusing on the delicate process of coordination where the old and new meet.
According to the intensity of representation, it has been subdivided by three systems. The first method is to describe and explain the originality of the museum as an independent individual relic. The second is a method of reproducing the relationship between multiple elements, beyond their individual properties. The third method of representation is the most active, and it refers to the comprehensive representation of spatial and architectural situations. In terms of inducing the context of the past and the practical experience that follows it, it can be viewed as the most strategic representation of the encounter between the past and the present, which is the main theme of the Acropolis Museum. It has been confirmed that the situation of the Acropolis Slope, the Erechtheum Terrace, and the Parthenon Gallery on the top floor are the most effective examples of contextual representation.
In the overall composition of the museum, the flow of movement of the beginning, the middle, and the end of the visit was analyzed with the key concept of experience. In addition to each floor's exhibition contents, based on the architect's sketches, the narrative elements inherent in the flow of movement were derived. In addition, in the experience of viewing the exhibition, the stimulus devices that convey the message of a living heritage are categorized in detail. It shows the uniqueness of the Acropolis Museum's unique methods of heritage reproduction in terms of layering floor using permeable materials, structural gestures, regular patterning, and autonomous choice on movement. In this respect, the Acropolis Museum is an exemplar for recreating authentic heritage.