Memorial Park Gamlebyen.
St. Hallvard's Church from 1130 var devoted to Oslo's patron saint St. Hallvard. It had the shape of a Roman basilica, very much like Old Aker Church. In 1260 it was expanded with a gothic chancel. The church was used until 1650. From then on it deteriorated quickly and the last remnants of the stone walls were used around 1780 to repair the road between old Oslo and the new city Christiania.