St. Olav's Cathedral is the cathedral of the Roman Catholic Diocese of Oslo. At the time of construction, this church, being built at Hammersborg, near the graveyard of Our Saviour, was located in the countryside outside the then city of Oslo. The work was funded by private donations and fundraising abroad, the most generous individual donor being Queen Josephine, who was a Catholic herself.
The first mass of the church was celebrated on August 24th, 1856, but as there was no Roman Catholic bishop in the country, the church was not consecrated until August 8th, 1896. When the Roman Catholic Diocese of Oslo was established in 1953, St. Olav's was chosen as the episcopal seat and was elevated to the rank of cathedral. It is the second Catholic cathedral in Oslo. The St. Olav's Cathedral was visited by Pope John Paul II when he visited the Scandinavian countries in 1989.
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.