A 13th-century monastery has been discovered beneath a football pitch in Denmark
An ordinary football pitch in Roskilde, Denmark, concealed almost an entire medieval monastic complex beneath it. Using ground-penetrating radar, archaeologists detected walls, rooms, a courtyard and the church of St Clare’s Monastery, founded in the 13th century, lying about a metre below the surface. Experts knew that the monastery had once stood in this area, but it was thought that it had been almost completely dismantled following the Reformation.
An unexpected discovery has been made in the Byparken area of Roskilde, where there are plans to build an underground car park beneath an existing sports pitch.
Historical sources indicate that a convent dedicated to Saint Clare stood on this site during the Middle Ages. Consequently, ahead of any potential construction work, experts decided to survey the site using ground-penetrating radar.
This method allows the underground space to be investigated without excavation: the device sends out electromagnetic pulses, and the differences between soil, masonry and other structures are reflected in the resulting maps.
The result turned out to be far better than the archaeologists had expected.
Details
The scan revealed numerous remains of medieval buildings approximately one metre below the modern surface.
The ground-penetrating radar maps revealed four monastery wings, arranged at right angles to one another and surrounding an inner courtyard.
The researchers also identified individual rooms, column bases, elements of covered galleries and other architectural structures.
According to the experts, the east wing is particularly well-preserved. Traces of room divisions and the bases of vault supports are visible there.
In the south wing, the researchers identified the monastery church.
The Monastery of St Clare was founded in Roskilde in 1256.
In the Middle Ages, the town was one of Denmark’s most important religious and political centres. There were as many as five monasteries here, and the influence of the Church was closely intertwined with royal power.
Following the Reformation in the 16th century, the Convent of St Clare ceased to exist. Its buildings were dismantled; historical records indicate that around half a million bricks were sold for the construction of Selsø Castle.
Due to the extensive demolition, it was long assumed that virtually nothing remained of the complex.
Now, ground-penetrating radar has revealed a completely different picture.
Experts describe the scan results as exceptionally clear.
GPR data usually requires complex interpretation, and individual structures can be difficult to distinguish from natural features of the ground. In Roskilde, the outlines of some structures were so distinct that researchers could see them whilst working on the football pitch.
According to experts, these are among the clearest ground-penetrating radar images of a medieval monastic complex ever obtained in Scandinavia.
In addition to the four main wings, the data suggest the possible existence of further buildings outside the monastery courtyard.
Despite the striking images, this is, for the time being, strictly a geophysical survey rather than a full-scale archaeological excavation of the complex.
Ground-penetrating radar allows the probable location of walls and other structures to be determined; however, excavations are required to confirm their condition and the precise dating of individual elements.
The next stage could involve trial trenches on the site where a car park is planned.
Further work will depend, amongst other things, on the decision of Roskilde Municipality.
The discovery has created an unusual situation.
Of the five known medieval monasteries in Roskilde, four are already listed. The site of St Clare’s Monastery did not have this status — largely because it was believed that any significant remains of the complex had long since disappeared.
It has now emerged that a significant portion of the medieval architecture may be preserved beneath the football pitch.
Archaeologists wish to identify which sections are best preserved and find a solution that will allow the site to be studied whilst preserving the most valuable structures.
Why this is important
The discovery offers a rare opportunity to investigate the layout of a medieval convent with virtually no interference from modern buildings.
Much of historic Roskilde has long since been built over, making it difficult for archaeologists to gain a comprehensive understanding of the convents that once shaped the city’s appearance.
The football pitch proved to be an exception: the area has been virtually untouched by later major development.
This is precisely why, some 770 years after the convent was founded, its wings, rooms, inner courtyard and church can still be made out beneath the ground.
Source
Organisations: ROMU, National Museum of Denmark, Norwegian Institute for Cultural Heritage Research (NIKU), 2026.