Kristiansten Fortress

In the mid 17^th century, the city of Trondheim was protected by the Nidelva, but was vulnerable to attack from the east. Construction of new fortifications began in 1681, and in 1685 Kristiansten Fortress was completed. The fortress saw action in the autumn of 1718, during the Great Northern War, when Swedish forces attempted to capture Trondheim as part of a second invasion. The forces were repelled thanks to the strength of Kristiansten and other fortifications. 
During the Second World War the Nazis used the Fortress as an execution ground for Norwegian Patriots, and in the legal purge that followed WWII it was the official place of execution for condemned traitors and war criminals. These days it boasts a picnic area and a retro themed café specialising in exquisite hot chocolate.