Grijzestad Citadel is an 18th century fortress in Grijzestad, situated above the old town.
In 1703 the War of the Spanish Succession was taking place and there were fears of an impending attack on Brunant. Work began on the citadel that year. The fortress was to be built on a hill overlooking the town. The defenses would incorporate the town walls, which would be linked to the fort. Work ended in 1712, but by the war's end (1715) the island had not been invaded.
Only until 1757 would the fort see combat. The French invaded Brunant shortly after taking Minorca and in 1757 they launched a Siege of Grijzestad. Beginning on March 18th this would become the longest siege in Brunanter history. Only in late September would the French be able to enter the town and even then the strategic positioning of the fort (and its cannons) led the French to abandon Grijzestad for the cover of trenches around the town. On June 2, 1758 the town was finally relieved. During the Invasion of Brunant in 1784 Grijzestad resisted invasion and a battle was fought in the town. Though the fort was well defended, the town wall was breached and the garrison was coerced into surrendering.
During the German invasion in 1941, Grijzestad was the site of a rather one-sided battle. German armored units easily entered the town and the citadel's 19th-century guns could not prevent that. Later, paratroopers were parachuted onto the fort and were in control.