St. Clement's Church Ruins, Oslo

Saint Clement's Church, formerly one of Oslo's Roman Catholic parish churches, now stands as ruins within the Medieval Park. Dedicated to Saint Clement, a 1st-century pope and patron saint of seafarers due to his martyrdom by drowning with an anchor around his neck, this stone church featured a distinctive double-nave floor plan and a tower. The entrances graced its southern and western facades, while the central choir axis boasted three supporting pillars for the roof. As the tides of the Protestant Reformation swept in, the church fell into disuse and likely met its end in 1540.

Architect Gerhard Fischer uncovered and surveyed the ruins in 1921, though their significance remained largely overlooked for years. In the years 1970–71, archaeologist Ole Egil Eide undertook further excavations beneath the church's foundations. His work unveiled a wealth of history, including 81 ancient burials predating the stone church. These graves were organized into seven distinct layers beneath the church.

Beneath a layer of sand, Eide's exploration revealed another 60 graves. His assessment suggests the presence of not just one, but possibly two earlier churches – potentially stave churches – preceding the construction of the stone church around 1100. Radiocarbon dating pinpointed the oldest burials to roughly 980-1030, presenting some of Norway's earliest Christian interments.