The Oscarsborg Fortress Museum is located on an island in the Oslofjord in Norway. It was originally built in the 19th century to protect the capital, Oslo, from naval attacks. The fortress played a significant role during World War II, particularly during the German invasion of Norway in 1940. Today, the museum showcases the history of the fortress and its military significance. Visitors can explore the well-preserved buildings, including the coastal artillery and various exhibits that highlight the fortress's role in Norwegian history. The scenic surroundings also make it a popular destination for tourists.