One of Oslo's "must see" sights is the Opera House. A building inspired by the Norwegian nature to resemble an iceberg by the waterfront and the people on it is meant to look like tiny penguins. There aren't many places in the world where you are allowed to climb on top of a building, but the Oslo Opera house encourages visitors to head up on the rooftop for a great view of the city! There are two pathways up, which seems to be very accessible in the summer but since we where there in December it was very slippery and lots of ice spots to look out for. We visited the Opera on our first day but decided to come back the day after as well when the sun came out so we had a chance to catch the sunset from the roof.