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:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.