Fort Kijkduin is a Napoleonic-era coastal fortress built into the dunes at the very tip of the North Holland peninsula. Construction was ordered by Louis Napoleon, King of Holland, and the fort was completed in 1811. It was designed to control the Marsdiep strait — the deep channel between the mainland and Texel — and to guard Den Helder's naval anchorage from attack by sea. The fort is circular in plan, with a moat, earthwork bastions, and a central keep, all partially buried in the dunes.
The fort houses a small aquarium and is open to visitors in the warmer months. The surrounding area is excellent for a coastal walk: the sea dike offers clear views across the Marsdiep to Texel, and a colony of grey seals regularly hauls out on the sandbanks below. Binoculars are useful. The Lange Jaap lighthouse stands a few hundred metres to the north and makes a natural second stop on the same walk.