Oslo was formerly called Christiania and officially restored its original name in 1925.
The city was founded by King Harald Hardrada around 1049, according to the traditional account. After a major fire in 1624, King Christian IV of Denmark-Norway rebuilt the settlement near Akershus Fortress and named it Christiania after himself. The spelling Kristiania was also used.
Norway’s parliament resolved in 1924 that the city’s name would return to Oslo, and the change took effect on 1 January 1925. The restored name reflected the city’s medieval origins and its earlier identity.
The name change is sometimes simplified as a switch from Christiania directly to Oslo, but Kristiania was also an important official spelling. Oslo is now Norway’s capital and sits at the northern end of the Oslofjord, surrounded by forested hills and islands.