Fodor's Expert Review Kristiansten Festning
Built by J. C. Cicignon after the great fire of 1681, the Kristiansten Fort saved the city from conquest by Sweden in 1718. During World War II, the German occupying forces executed members of the Norwegian Resistance here; there's a plaque in their honor. The fort has spectacular views of the city, the fjord, and the mountains. Some walls are unsecured, so take care when walking, and mind your children.