Old Aker Church
Old Aker Church () is a medieval era church located in Oslo, Norway. An active parish, the church is the oldest existing building in Oslo. The church is surrounded by Old Aker Cemetery.
Old Bishop's Palace in Oslo
The Old Bishop's Palace in Oslo ("Oslo Bispeborg") was the residence of the Roman Catholic bishops of Oslo. The estate is located in what is now called Gamlebyen (old town) in Oslo, Norway. Various remnants of the medieval bishop's original palace are still visible.
The construction was begun around 1210 by the then bishop, Nikolas Arnesson, continuing through to the early 14th century. The palace built in stone replaced a previous bishop's residence built in wood, established in the 12th century. The main buildings were surrounded by tall walls, and from a tower, a wooden bridge connected the palace to the neighboring Hallvards Cathedral. The palace was built like a fortified castle. 
Together with the cathedral, the palace was not only a religious centre in Middle Age Oslo, it was also of significant political importance. The first agreement of union between Norway and Sweden was signed in the bishop's palace just after the death of Håkon V of Norway, in 1319.