Just over a kilometer outside of Trondheim, in the Trondheimsfjord, is the fortified island of Munkholmen.
In the summer, you can take a shuttle boat from Ravnkloa to visit the island, where you can see the well-preserved round tower belonging to the former Benedictine abbey of Nidarholm, founded in the 12th century.
This site is now occupied by a fort built in 1658, the Gammel Festning, as well as more recent fortifications left behind by the German occupiers in World War II, when it was used as an anti-aircraft gun station.
