Here's an ideal itinerary for 2 days in Oslo:

Day 1:

• Start your day with a visit to the iconic Vigeland Sculpture Park. This park is home to over 200 bronze, granite and cast iron sculptures created by Gustav Vigeland.
• After exploring the park, head to the nearby Frogner neighborhood for lunch. There are plenty of cafes and restaurants to choose from, but we recommend trying some traditional Norwegian cuisine at Kolonihagen Frogner.
• In the afternoon, take a stroll through the trendy Grünerløkka district. This area is known for its street art, independent shops, and vibrant nightlife.
• For dinner, head to Mathallen Oslo, a food hall that offers a variety of cuisines from around the world. You can find everything from sushi to pizza to traditional Norwegian dishes here.

Day 2:

• Start your day with a visit to the Oslo Opera House. This stunning building is located right on the waterfront and offers incredible views of the city.
• After exploring the Opera House, head to the nearby Akershus Fortress. This medieval castle has been standing since the 13th century and offers a fascinating glimpse into Norway's history.
• For lunch, head to the Aker Brygge waterfront area. This bustling district is home to a variety of restaurants and cafes, as well as a lively outdoor market.
• In the afternoon, take a ferry to the nearby Bygdøy peninsula. Here you'll find several museums, including the Viking Ship Museum and the Kon-Tiki Museum.
• For dinner, head back to the city center and try some traditional Norwegian seafood at Fiskeriet Youngstorget.

Of course, this is just one possible itinerary - there are plenty of other things to see and do in Oslo depending on your interests!