Wilhelmstein Island Fortress

From the shore at Steinhude, Wilhelmstein looks like a small green islet with a few houses, but it hides one of Europe's most unusual fortresses. Count Wilhelm of Schaumburg-Lippe had an island built in the middle of Lake Steinhude from 1761 and put a fortress on it to protect his tiny state of just 17,000 people. People mocked it as a hobby of a cannon-mad count, until it actually withstood a siege in 1787. Today you reach it by boat and can visit the casemates, the commander's quarters and the tower.

History: a man-made island

From 1761 to 1765 locals brought about 30 cubic metres of sand, gravel and stone every working day, by fishing boat in summer and by sledge over the ice in winter; a 1.2-km canal was dug just for the transport, and the workers were paid. Between 1765 and 1767 a star-shaped redoubt with four bastions rose here, surrounded by 16 small outwork islands with gun positions, workshops, a hospital and even a windmill. In 1777 there were 166 cannons. Around 1810 the gaps were filled in, creating today's almost square island about 100 metres across.

The count also founded a military school here; its most famous pupil was Gerhard von Scharnhorst, later the great Prussian army reformer, who arrived in 1773 aged 18. In 1787 troops from Hesse-Kassel occupied the county, but about 150 men held out on Wilhelmstein. Some 2,800 besiegers could not get their guns close enough across the marshy shore, Hanover kept the island supplied, and the Hessians withdrew when Prussia and Hanover gathered troops.

What to see

• Casemates with reconstructed living quarters and cells.
• Commander's quarters, where civil weddings are held today.
• The tower, with views over the whole lake; an observatory from 1774.
• Exhibition of maps, mortars, cannon barrels and muskets.
• Steinhuder Hecht: The count's design for the first submarine built in Germany, meant to be driven by a fish tail.

Opening hours and tickets (as of October 2026)

Open daily from 20 March to 31 October 2026; closed in winter because of a boating ban on the lake. Admission €5, children 4–13 €2, younger children free; the boat is extra. Dogs are welcome on the island but not inside the fortress.

Getting there

Boats leave from the Strandterrassen pier, Meerstraße 2 in Steinhude, and from Mardorf; the traditional "Auswanderer" boats take about 25 minutes. Both villages have parking.

Tripto tip

Allow two to three hours including the crossing, climb the tower and bring a jacket for the open boat.