Begin your day walking down Karl Johans Gate, Oslo's main promenade and a hive of activity in summer. Start from the Royal Palace (Kongelig Slottet) and continue along until you reach Oslo S Station on the east end. In between these two points, take in Oslo University (Universitet) and Stortinget, the Parliament building. In between these two attractions, you can turn south down Roald Amundsens Gate and pass the Nationaltheatret (National Theater), the spiritual home of Norwegian playwright Henrik Ibsen, to see murals inside the Rådhuset. In the afternoon, walk to the rear of the town hall to view the magnificent Oslo fjord from one of the docked Viking ships at Aker Brygge, a disused shipyard area rebuilt into a shopping and commercial center.
Follow the itinerary above on Day 1, and on the second day take in the museums at Bygdøy, farther west along the Oslo fjord. Catch Ferry 91 from Pier 3 at the rear of the Rådhuset beside Aker Brygge. Start with the open-air Norsk Folkemuseum, where you can wander among more than 170 examples of traditional wooden housing from as far back as the 14th century. Next visit the Vikingskiphuset, which has the best-preserved Viking ships in existence. Continue along to either the Kon-Tiki Museum to learn about the travels of famous Norwegian explorer Thor Heyerdahl, or the Fram-Museet to board the legendary polar vessel, Fram.
Follow the itineraries for Days 1 and 2 above. On Day 3 visit the Vigelandsparken sculpture park. Norwegian artist Gustav Vigeland (1869-1943) spent a lifetime creating his masterwork -- a glorious park with more than 200 bronze, granite, and steel sculptures. Afterward, take the T-bane line 1 to Oslo's ski fields at Holmenkollen, no matter what the season. Experience the Holmenkollbakken ski museum, then head to the historic Frognerseteren restaurant to sample Norwegian specialties like reindeer and salmon.