St. Clement's Church or Klemet's Church was one of the Roman Catholic parish churches of the old Oslo. It was a stone church with a tower, and it was one of the very few churches we know with the double-nave floor plan. Along the middle axis of the choir there were three powerful pillars that held the roof. The church went out of use after the Protestant Reformation, and expect it rather quickly was in ruins.
The church was exposed and examined through excavation by arcitect Johan Adolf Gerhard Fischer in 1921. Then remained for years unnoticed during Loeng bridge. In 1970-71 was archaeologist Ole Egil Eide opportunity to dig further into the ground under the church, and found traces of burials older than the stone church, 81 in all. His interpretation is that there have been at least two churches, presumably stave churches, on the spot where the stone church was built around 1100. The oldest of the graves are dated to the radiological 980-1030, and were some of the oldest Christian burials found in Norway. Ruins of Clement's Church is now exposed and is included as part of Middelalderparken in the Old Town of Oslo.
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.