Located in a castle built in the seventeenth century over a watchtower, of which the construction was ordered by King Philip III. During the twentieth century it served as a barracks, prison of officers and battery of salvos to greet the warships. In 1981 it was declared Museum of Military History and in 1997 the constitution articles of the Consortium of the Castillo de San Carlos were signed.

It features an important collection of ancient weapons and Mallorcan cartography from the Middle Ages to the twentieth century. It has 10 rooms, among which stand out those dedicated to the French prisoners at Cabrera during the War of Independence and to General Weyler, the latter located in the original entrance of the castle. The hall 1 houses the Lorente collection, one of the best in Europe in terms of handguns and knives.