The Oslo Cathedral is the cathedral of the Lutheran diocese of the same name, belonging to the Church of Norway, and the national cathedral of Norway.
El Salvador is the third cathedral in the city of Oslo. It was built in the second half of the 17th century to replace the previous one, the Trinity Cathedral, destroyed by a fire.
An unpopulated place was chosen for its location, near the center of the city. Its construction material was Dutch brick and its tower was not as high as it is today. Consecrated the cathedral in 1697, the sacristy was completed in 1699 and the interior works continued until the early 1720s, largely due to the outbreak of the Great Northern War (1701-1720). In 1718 the clock was placed on the tower and at the beginning of the 1720s the first organ was installed, the work of the Swedish Carl Gustav Luckvitz, leaving the cathedral completely finished.
In 1850 it was restored, on the occasion of the 800th anniversary of the city. Construction coordination was carried out by the French architect Alexis de Chateauneuf. The interior of the cathedral was changed to the neoclassical style, very much in vogue then and the tower, considered quite low by the population, was raised considerably and a dome was placed, giving the building a majestic appearance. In the absence of Dutch brick, the new works were executed with red brick.