A medieval monastery long thought to have vanished has been located beneath a sports field in Roskilde, Denmark. Ground-penetrating radar has revealed well-preserved remains of Sankt Clara monastery, built in the 13th century.
Among the clearest in Scandinavia: “This is the first time I’ve documented such a well-preserved monastery complex with ground-penetrating radar, and in my assessment, these are among the clearest radar results from a monastery complex in Scandinavia,” says Arne Abel Stamnes. Credit: National Museum of Denmark/NIKU
The ruins lie about one meter below the current ground surface. Researchers found the remains during a survey linked to plans for an underground parking facility beneath the sports field at Byparken.
Historical records place a convent at the site during the Middle Ages. ROMU, Roskilde Museum, used ground-penetrating radar to learn how much of the complex had survived. The method sends electromagnetic waves into the ground and records signals reflected by buried structures.
Archaeologists knew Sankt Clara had stood at the site, but they didn’t know how much of the complex from 1256 was still intact. The radar survey produced clear results and now gives researchers a strong base for future work, said ROMU archaeologist Jesper Langkilde.
Sankt Clara was one of five medieval monasteries in Roskilde. The city served as an important center for church and royal power for many years. After the Reformation in the 16th century, the monastery was closed and demolished. Historical records say about half a million bricks from the site were sold to Selsø Castle.
For this reason, researchers long thought little or nothing of the monastery had survived. Later building work also reduced knowledge about the layout of Roskilde’s medieval monasteries. The open grass field offers a rare chance to study Sankt Clara without earlier buildings covering the site.
During data collection, NIKU archaeologist Arne Abel Stamnes could follow the results on screen in real time. About one meter below the ground surface lie the well-preserved remains of Sankt Clara Monastery from 1256. Credit: Jesper Langkilde/ROMU.
The survey was a joint effort by ROMU, the National Museum of Denmark, and the Norwegian Institute for Cultural Heritage Research, NIKU. NIKU archaeologist Arne Abel Stamnes carried out the radar measurements. He has wide experience with geophysical surveys of cultural heritage sites.
The radar data mapped several parts of the monastery. Researchers identified room layouts, covered walkways, and a church in the south wing. The east wing appears especially well preserved. Clear traces of vault pillars and room structures were visible in the data.
Stamnes said the results were unusually clear. The buried structures were visible while the survey team drove across the soccer field. He described the find as the best-preserved monastery complex he has recorded with ground-penetrating radar. He also judged the results among the clearest radar records from a monastery site in Scandinavia.
NIKU building archaeologist and monastery expert Regin Meyer reached a similar view. The radar images show four monastery wings set at right angles around a central courtyard. Researchers also see many room divisions, pillar foundations, and the covered walkways typical of a monastery layout.
The data also point to structures and buildings outside the main four-sided complex. Such details show how much architectural evidence still lies below the surface.
Sankt Clara is the last of Roskilde’s five known medieval monasteries to be found. The other four sites have protected status. The Sankt Clara site doesn’t have the same status because researchers once believed its remains had been lost.
The next stage will involve test trenches and archaeological work in the area planned for the parking facility. Researchers will use those results with the radar maps to plan any larger excavations.
The work aims to document the buried remains and find ways to protect the best-preserved parts of Sankt Clara for the future.