Fortaleza de San Carlos de la Cabaña, known as La Cabaña (Fort of Saint Charles), is an 18th-century fortress complex, the third biggest in the Americas, located on the elevated eastern side of the harbor entrance in Havana, Cuba. The fortress served as both a military base and prison for over two hundred years, for both Spain and an independent Cuba. La Cabaña was used as a military prison during the Batista regime.