It was initially built as a hospital in 1280, and later it became St. Hans Monastery. During the Middle Ages, it was Denmark's second-largest monastery and was owned by the Knights of St. John. On March 18, 1848, the state took over the castle, and Odense Municipality purchased it in 1907. Odense Castle holds an exciting place in national history. Today, Odense City Council uses the castle, and it can only be viewed from the outside.