Rosenkrantz Tower (Norwegian: Rosenkrantztårnet) is a tower that derives its name from governor Erik Rosenkrantz (1519-1575) who was governor of Bergenhus Fortress from 1560 to 1568. During his administration, the tower received its present shape and structure. The oldest part of the building is made up of a medieval tower built during the reign of King Magnus the Lawmender in the 1270s as part of the royal castle in Bergen.
The keep was slightly modified circa 1520, then extensively modified and expanded in the 1560s by Scottish stonemasons and architects in the service of Erik Rosenkrantz to attain its present form. Rosenkrantz' building contained dungeons on the ground floor, residential rooms for the governor higher up, and positions for cannons on the top floor. In the 1740s, the tower was converted to a magazine for gunpowder, a function it served until the 1930s. The whole building has been open to the general public since 1966. Today, the tower serves primarily as a tourist attraction.