Fort Napoleon in Ostend is a polygonal fort built in the Napoleonic era. It has recently been restored and is open to the public.
France had occupied the Austrian Netherlands during 1792 and 1793 in the Flanders Campaign of the French Revolutionary Wars. During the War of the Fifth Coalition, Napoleon Bonaparte expected a British assault from the sea on the port of Ostend, and the fort was constructed in the sand dunes close to the mouth of the harbour in 1811. The British attack never materialised and the fort was used as for troop accommodation and as an arsenal until the end of the French occupation in 1814 when it was abandoned.During World War I, the fort was used as accommodation for a German headquarters, and decorated with murals by German soldier Heinrich Otto Pieper.
Wikipedia https://en.wikipedia.org/wiki/Fort_Napoleon,_Ostend
Address 13 Vuurtorenweg, Oostende 8400, Belgium
Coordinates 51°14'20.381" N 2°56'3.692" E