Construction of this fortress began in 1308, along the Norwegian-Swedish border. After its completion, the fortress was attacked/or besieged 14 times, but was never successfully captured. One battle tells of a volunteer who saved the fortress from attackers in a last-ditch attempt by igniting the ammunition stores, causing an explosion that decimated enemy forces. In later centuries, the fortress was used as a prison for commoners and royalty alike. The fortress is open daily during spring and summer from 10 AM to 5 or 6 PM, depending on when you visit. There is a small entrance fee (50 kr for children, 100 for adults), and some sections may be closed off for safety during ongoing restoration. The trails around the fortress perimeter are free to access. There are several places to eat nearby, and the fortress is accessible by bus. (Note it's not a wheelchair-friendly place!) Activities include guided tours, archery, and some other fun activities designed for children. Live events are also sometimes hosted, and there are special activities for Christmas and Halloween.