Built by Hakon V in about 1300 according to the usual feudal castle plan, the fortress faces the sea in defiance of all attempts to invade from this direction. It was burned, and then Christian V turned it into a Renaissance palace at the start of the 17C. The monarchy abandoned it from the 19C in favour of the Royal Palace, and it has been used for official functions since. A pretty place for a walk, one can take in some lovely views of the fjord here.