Medieval bishop’s stone manor discovered in Turku’s Koroinen

Archaeologists have uncovered the ruins of a medieval bishop’s stone manor in Turku’s Koroinen district, public broadcaster Yle reports.

The discovery was made during excavations in June, involving a research team and around 20 amateur archaeologists from Finland, Sweden, and the UK. The site, located a few kilometres from the city centre, was once the first administrative hub of the Finnish Church.

Excavations focused on a ruin previously identified in the 1970s as a stone building, as well as traces of Iron Age activity. Instead, researchers found the remains of a large stone or possible brick building, complete with floor levels and internal walls. The full extent of the structure remains unclear, but it had multiple storeys and was at least 10 metres wide.

“We’re not accustomed to seeing stone building remains of this kind outside Turku’s medieval urban area,” said Janne Harjula, a university lecturer in archaeology at the University of Turku.

The building’s size, decorative details, and likely heating via a tiled stove suggest a wealthy owner. Preliminary findings indicate it was a bishop’s stone manor abandoned after the Reformation, with its ruins later repurposed as a romantic pavilion in the mid-17th century.

Signs of fire damage were found, but the primary cause of abandonment appears to be subsidence due to the clay-rich soil, a common issue in Turku, according to archaeology professor Georg Haggrén.

Excavation sites have since been backfilled and restored. Further research is planned for 2027–2028 to determine the building’s full scale, refine its dating, and clarify its use. No evidence of Iron Age settlement or activity was found in the areas studied.