According to the Nordic sagas, Oslo was founded by King Harald Hadrade in 1048. It has been the country's capital since King Hakon V (1299-1319) took permanent residence in the city and started the construction of the fortress. The year 1624 was marked by a disastrous fire after which the city was rebuilt at a new site and called Christiania (only in 1925 was the original name of Oslo restored). Christiania gradually developed as a commercial and cultural center. The Royal Palace, the Parliament and the University were built in the 19th Century. Oslo was the home of playwright Henrik Ibsen, artist Edvard Munch and Nobel prize winners Knut Hamsun and Sigrid Undset.

Arkeshus Fortress was erected by King Hakon V to protect the city. It resisted successfully a series of sieges, and was actually never captured by an enemy. In the 17th Century, King Christian IV had it reconstructed as a Renaissance castle. In  1940 the fortress surrendered to Nazi Germany as the Norwegian government decided to evacuate the capital. Today the castle houses the Museum of the Armed Forces and the Museum of the Norwegian Resistance. The Royal Mausoleum is the burial place of King Haakon VII, Queen Maud, King Olav V and Crown Princess Martha.

The Royal Palace was built in the 19th Century and is used as the official residence of the Norwegian monarch. It was designed by the Danish architect Hans Ditlev. The palace is open for organized tours.

The Parliament building also dates back to the 19th Century and was designed by Emil Victor Langlet.

The Vigeland Sculpture Park is probably the best known park in Norway, the work of the sculptor Gustav Vigeland. A famous sculpture is the Monolith, a 14 metre-tall column  carved from a single block of stone. 

A must-see in Oslo is the Munch Museum whose collection contains about a half of all works by Edvard Munch (about 1100 paintings), about 15,000 prints, plates, books and other items. A version of his famous painting 'The Scream' can be seen at the National Gallery.

Oslo is proud of the heritage of the great Norwegian explorer and writer Thor Heyerdahl. In 1947, he embarked on an expedition designed to prove that people of South America may have reached and settled in Polynesia in pre-Columbian times. He built a wooden raft using native South American materials and drawings made by the Spanish conquistadores, called it Kon-Tiki after the Inca sun god, and sailed with a crew of five men 4,300 miles across the Pacific to Tuamotu Islands to prove his hypothesis. The subsequent book Kon-Tiki, describing the expedition, became a best-seller. The original raft can now be seen at the Kon-Tiki Museum.

The Viking Ship Museum is a unique exposition featuring ships from Tune, Oseberg and Gokstad, as well as finds from a Viking cemetery.  The Vikings were strong and fearless warriors and great seafarers, and their long slender ships would sail all the way to the Mediterranean and Byzantium, striking unexpectedly and filling their enemies' hearts with terror.

The Museum of Cultural History has a large open-air exhibition containing 155 buildings from different parts of the country.

Oslo was the host of the 1952 Winter Olympics, and continues to offer excellent facilities for winter sports: eight alpine runs, hundreds of kilometers of cross-country runs, biathlon facilities and the legendary Holmenkollen ski jump.