This fortress is a bit grim for us, but the view from its precincts is reason enough to visit. Located about 2km (1 1/4 miles) east of the center of town, this is a stone-sided, thick-walled vestige of the military power of the army that occupied Trondheim during the 17th and 18th centuries. Built by the Danes between 1681 and 1682 as a defense against the Swedes during the reign of Christian IV, it alone is credited with repelling the attacks of the Swedish army in 1718, and thereby saving Trondheim from foreign occupation. It was constructed according to the most advanced military wisdom of its day, in a nine-sided design that might have been influenced by the French military architect Vauban. Between 1816 and 1901, it functioned as the headquarters of Trondheim's firefighting brigades. Under the Nazi occupation, the fort was used as a place of execution for members of the Norwegian Resistance; a plaque has been erected in their memory. On warm days, expect to see sunbathers and families with children playing on the verdant lawns that have replaced the muddy, pounded-earth floor of the historical fort. From its ramparts, you'll see the best panorama in town, encompassing fjords, towers, and the rest of Trondheim.