Old Aker Church (Gamle Aker kirke) is Oslo's oldest remaining building and the only remaining church from the Middle Ages. It is assumed that it was built around the year 1150. It is a stone church, built as a three-naved Roman-style basilica.
The church has been pillaged and ravaged by fire several times. The oldest part of the surrounding churchyard dates back to the 12th century. The church has a baroque pulpit and baptismal font from 1715. The tower was built in 1861.
The church was built over an old silver mine, Akersberg which was in use since the early Viking age. The mines are mentioned in the 1170 Historia Norvegiae. The mines must have been the inspiration for a number of stories about the church having hidden silver treasures and even dungeons with dragons.
References:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.