Memorial Park With St. Olav's Monastery & St. Hallvard's Cathedral is a historical landmark in Oslo, known for its preserved ruins of Hallvard's Cathedral. The cathedral, which served as a cathedral in medieval Oslo, was built under King Sigurd Jorsalfare in the first half of the 12th century. Hallvard, the city's patron saint, is central to the park's historical significance.
The ruins include an altar cross from the 13th century, which is still visible in the park. The southern part of the ruins was covered with a concrete lid in the 1960s, which has contributed to the preservation of this important cultural heritage. The cathedral was damaged in a fire during the attack on Oslo in 1137, marking a significant event in the city's history. Memorial Park is therefore an important place for both locals and visitors who want to learn more about Oslo's medieval history.