Using Ground Penetrating Radar (GPR) to Locate the Remains of the Jaundole (New Dahlen) Castle Near Riga, Latvia
Abstract
1. Introduction
1.1. Medieval Historical Background of the Riga Region
1.2. Dole Island, the Dry Daugava and Daugava Rivers, and Riga Reservoir
2. Historical and Iconographic Description
2.1. Historical Context for Vecdole Castle
2.1.1. Historical Timeline and Related Events for Vecdole Castle (1226 to 1355) [15]
- Castle first mentioned in documents on 15 May 1226.
- On 31 March 1255, Pope Alexander IV confirmed to the Archbishop of Riga, Albert II, in documents held by the Vatican, that the Archbishop had the right to Vecdole Castle on Dole Island.
- Despite the Pope’s decision to award the castle and Dole Island to the Archbishop of Riga, the Dolens unofficially held the castle until 1276.
- In 1276, Archbishop Johann I “officially” returned the castle to the Dolen family; however, Archbishop Johann II in 1288 again took the castle and the island away from the Dolen family and presented ownership to the Dome Chapter.
- In 1297, a war broke out between the Archbishop of Riga, the people of Riga, and the Livonian Order, which led to the eventual destruction of Vecdole Castle, probably in 1298.
- By all accounts, the castle was not rebuilt, and it is last mentioned in documents in 1348 and 1355, when the Archbishop confirmed the rights of possession for Dole Island and the most likely ruined Vecdole Castle to the Dome Chapter, which had taken control in 1288.
- In these 1348 and 1355 documents, the castle is referred to as the first Dole Castle, which indicates that there was already a second Dole Castle on the island.
2.1.2. Historical Interpretations
2.2. Historical Context for Jaundole Castle
2.2.1. Historical Timeline and Related Events for Jaundole Castle (1359 to 1628) [16]
- The Dome Chapter built a second Dole Castle, which was first mentioned in historical documents in 1359.
- The new Dole Castle was noted to be minor, with its size estimated to be between 35 × 35 m and 45 × 45 m. On the ground floor was a warehouse for old weapons, a kitchen, and stairs to the second floor, which housed a hall, a small room, and seven rooms for guests. The castle also had a bakery, a brewery, five cellars, a granary, and a small church.
- In 1416, the Dome Chapter gave the castle to the Livonian Order, but in 1449, the Order returned it to the Chapter.
- In 1522, the Archbishop of Riga, Jasper Linde, gave the Dole (Jaundole) Castle to the Provost of the Riga Cathedral Chapter, and in the mid-16th century, the castle served as a refuge for the Archbishop’s servants.
- In 1561, the Livonian states ceased to exist, and in 1566, the control of Dole Island and, hence, Jaundole Castle passed to Poland, becoming a crown estate.
- In 1597, the famous Danish astronomer Tycho Brahe wanted to build an observatory on the island to observe the stars, but he did not receive permission.
- During the Polish–Swedish War in 1621, the Swedes captured the castle and quickly restored and modernized its fortifications.
- In 1627, the Poles captured the castle, and while retreating in 1628, they blew it up so that it would not fall back into the hands of the Swedes [16].
2.2.2. Iconographic Depictions Related to Jaundole Castle (1359 to 1628)
2.2.3. Historical Timeline and Related Events for Jaundole Castle (1628 to 1839) [16]
- After its destruction in 1627, the castle was no longer used as a military fortification, and over the years, the ruins were eventually covered with earth and practically disappeared.
- In 1631, the first manor estate, whose owner was a Swedish army officer, was established on Dole Island within two km of the Jaundole and Vecdole Castle sites.
- After the Great Northern War, which ended in 1721, possession of the manor estate changed hands many times.
- Already in the 18th century, almost nothing remained of the castle walls.
- In the 19th century, as depicted in an 1830 painting, the remains of Jaundole Castle were still visible on the land surface (Figure 6).
- In 1839, the Livonian Charitable and Economic Society published a map of Dole Island (Figure 7).
2.2.4. Iconographic Depictions Related to Jaundole Castle (1628 to 1839)
2.2.5. Historical Timeline and Related Events for Jaundole Castle (1898 to 2024)
- In 1957, Latvian archaeologist Andris Caune drew a plan of the remains of the walls of Jaundole Castle.
- In 1977, the Daugava Museum, which is located in the 1898 Dole Manor House, opened to the public [18].
- In 2024, a research team from Duquesne University and the University of Wisconsin-Eau Claire completed data collection using GPR to find the location of the buried remains of Jaundole Castle.
2.2.6. Historical Interpretations (1631 to 2024)
3. Materials and Methods
3.1. Methodological Background
3.2. GPR Methodology
4. GPR Results and Data Interpretation
5. Discussion
6. Summary and Conclusions
- (1)
- Identify the likely location, layout, and function of Jaundole Castle through historical sources.
- Two drawings of Jaundole Castle were found that indicate that the castle’s shape was square, with towers at each corner topped by a spire.
- A 1627 map exists on the Castles of Latvia (Jaundole Castle) website [16] that depicts the northern portion of Dole (Dahlen) Island and shows that Jaundole Castle was located at the confluence of the Lebjava and Dry Daugava Rivers. This map contains the inscription “has been blown up, but the fortifications are still there”, indicating that it was destroyed in 1627 or before.
- In a painting by A. Merkela from 1830 (see Figure 6), the ruins of Jaundole Castle can still be seen, with fertile farmland, associated with the main economic function of the castle, depicted across the Dry Daugava River.
- A small area containing the ruins of the castle could still be seen on the land surface in 1957.
- (2)
- Evaluate the effectiveness of ground-penetrating radar (GPR) for detecting its buried remains.
- GPR detected numerous reflection patterns in the subsurface within the five grids (see Figure 12), with the greatest concentration in grid 1.
- On average, the penetration depth in the five grids analyzed in 2024 was 2.5 m, with structural features related to the castle that are buried beneath the contemporary landscape detectable down to depths of at least 2 m.
- (3)
- Determine whether structural elements can be interpreted from GPR data to support future archaeological excavations.
- The reflection patterns present within the GPR grids, with grid 1 containing the most reflections, are linear, probably indicating buried Jaundole Castle wall locations, and, to varying degrees, circular, indicating rubble piles or other human-constructed features.
- Based on these discoveries, possible test excavation locations were provided to the director of the Daugava Museum and the stewards of the property, and it is probable that test excavations will verify that the GPR data reflection patterns and associated features in the cross-sections are associated with the remains of Jaundole Castle.
- In that case, additional GPR data will be collected to assist with the development of full-scale excavation targets, but no timeline has yet been developed for these excavations.
Supplementary Materials
Author Contributions
Funding
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
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Reeder, P.; Jol, H. Using Ground Penetrating Radar (GPR) to Locate the Remains of the Jaundole (New Dahlen) Castle Near Riga, Latvia. Heritage 2025, 8, 161. https://doi.org/10.3390/heritage8050161
Reeder P, Jol H. Using Ground Penetrating Radar (GPR) to Locate the Remains of the Jaundole (New Dahlen) Castle Near Riga, Latvia. Heritage. 2025; 8(5):161. https://doi.org/10.3390/heritage8050161
Chicago/Turabian StyleReeder, Philip, and Harry Jol. 2025. "Using Ground Penetrating Radar (GPR) to Locate the Remains of the Jaundole (New Dahlen) Castle Near Riga, Latvia" Heritage 8, no. 5: 161. https://doi.org/10.3390/heritage8050161
APA StyleReeder, P., & Jol, H. (2025). Using Ground Penetrating Radar (GPR) to Locate the Remains of the Jaundole (New Dahlen) Castle Near Riga, Latvia. Heritage, 8(5), 161. https://doi.org/10.3390/heritage8050161