What's a good 3-day itinerary for Oslo?

Day 1 stays along the Bjørvika waterfront. The Oslo Opera House opened in 2008, and the angled marble roof is accessible before the 10 AM box office. By 9 AM you'll have the white Carrara surface mostly to yourself, the fjord wind cool on your face. MUNCH sits 400 metres east. The 2021 building holds 28,000 works across 13 floors. Spend 90 minutes on floors 7 through 10, where The Scream and Madonna hang. Walk southwest to Akershus Fortress, built in 1290 and still a functioning military base. Entry is free. By 1 PM, cut through Kvadraturen to Engebret Café on Bankplassen 1, operating since 1857. The reindeer stew runs about 350 NOK, roughly 37 USD. Walk Karl Johans gate from Oslo Cathedral, consecrated in 1697, to the Royal Palace, completed in 1849. Stop at the Nobel Peace Center on the way to Aker Brygge. It opened in 2005 and admission is around 150 NOK. Dinner at Lofoten Fiskerestaurant, where grilled cod with brown butter costs around 380 NOK. The waterfront tables fill by 7 PM in June, when the sun still hangs high over the Oslofjord.

Day 2 heads west to Bygdøy. Catch the number 30 bus from Nationaltheatret at 9:30 AM for the 15-minute ride. The Norwegian Museum of Cultural History covers 14 acres of open-air exhibits, including a stave church from around 1200. The interiors smell of centuries-old tar and pine resin. Allow 2 hours. Walk 10 minutes south to the Fram Museum to see the polar vessel Roald Amundsen sailed to Antarctica in 1911. The Kon-Tiki Museum sits next door. Thor Heyerdahl's balsa raft looks impossibly fragile up close, the lashed ropes visibly worn. Lunch on Bygdøy tends to be overpriced, about 220 NOK for a forgettable sandwich. Take the bus back and eat at Lorry on Parkveien 12 near the Royal Palace, where the fish soup runs around 195 NOK. After lunch, tram 12 from Majorstuen drops you at Frogner Park's south gate. Gustav Vigeland worked on this installation from 1907 until his death in 1943. The 212 bronze and granite sculptures fill 80 acres. The Monolith, carved from a single granite block, stands 14 metres tall. Late afternoon light from the west side hits the figures best.

Day 3 shifts northeast to Grünerløkka, Oslo's former industrial quarter turned café district along the Akerselva river. Start at Tim Wendelboe on Grüners gate 1 by 9 AM. This single-origin roaster has been winning Nordic barista competitions since 2004. A pour-over costs 65 NOK. The room holds maybe 12 seats, and roast-warm air hits you at the door. Walk 8 minutes north to Mathallen Oslo in the Vulkan complex, a food hall with about 30 vendors. Try the brunost at Ostehuset or pick up smoked salmon at Vulkanfisk for around 120 NOK per 200 grams. After noon, take T-bane line 1 from Stortinget to Holmenkollen, a 25-minute ride that climbs 370 metres above sea level. The ski jump tower, rebuilt for the 2011 World Championships, gives a full panorama south over the Oslofjord. Admission runs around 170 NOK. On clear days the view reaches 60 kilometres. Take the same line back and finish at Olympen on Grønlandsleiret 15, a beer hall open since 1892. The pork shank with sauerkraut costs 295 NOK, and 18 taps pour mostly Norwegian craft.

Oslo is expensive by any standard, but the 72-hour Oslo Pass at 895 NOK (about 94 USD) covers all public transit and entry to over 30 museums, including MUNCH, the Fram Museum, and Holmenkollen. Buy it at the tourist information office inside Oslo Sentralstasjon. The Flytoget airport express from Gardermoen takes 19 minutes to Oslo S and costs 220 NOK. The regular Vy train takes 23 minutes for 117 NOK. Both depart from the same airport terminal level. Mind you, June weather in Oslo sits around 17°C with long, bright days. The sun sets around 10:45 PM and rises before 4 AM, which stretches golden hour to nearly 3 hours of soft Nordic light. That lingering twilight will wreck your sleep without an eye mask. Total walking across the three days comes to roughly 24 kilometres.