Old Aker Church
Old Aker Church was built as a three-naved Romanesque style basilica and constructed from limestone. It is believed to have been erected by King Olav Kyrre in 1080 as a church for all of Vingulmark, the historic area surrounding Oslo. The grounds of Old Aker Church were originally likely the former site of the regional thing during the pre-Christian period.
Oslo Cathedral
For almost 500 years, Hallvards Cathedral was the most important church in the city. After a great fire in Oslo during 1624, King Christian IV decided to move the city a few kilometers west to be protected by Akershus Fortress. Construction of a new church was begun in 1632, on the main square in the new city. After that, Hallvards Cathedral fell into disrepair and decayed.