Fortress of San Carlos de la Cabaña, Havana, Cuba.
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 fort rises above the 200-foot (60 m) hilltop, along with Morro Castle (fortress).
Construction of La Cabaña began in 1763 by King Carlos III of Spain, the controlling colonial power of Cuba, following the earlier capture of Havana by British forces (an exchange was soon made to give Havana back to the Spanish in exchange for Florida). Realizing that the city was not well enough defended and fearing further attacks following British colonial conquests in the Seven Years War, they now moved to build a new fortress to boost the defense of Havana. Replacing earlier fortifications next to the 16th-century El Morro fortress, La Cabaña was the second largest colonial military installation in the New World by the time it was completed in 1774 (after St. Felipe de Barajas fortification at Cartagena, Colombia), at great expense to Spain.
The fortress served as both a military base and prison, over the next two hundred years, for both Spain and an independent Cuba. La Cabaña was used as a military prison during the Batista regime.
In January 1959, Castro rebels seized La Cabaña. The defending Cuban Army offered no resistance and surrendered. Che Guevara used the fortress as a headquarters and military prison for several months. During his five-month tenure in that post (January 2 through June 12, 1959), Guevara oversaw the revolutionary tribunals and executions of suspected war criminals, political prisoners, traitors, chivatos (informants), and former members of Batista's secret police.
The complex is now part of a historical park, along with El Morro castle, and houses several museums open to the public. From there, every night a cannon shot rumbles at 9pm as the so-called "El Cañonazo de las 9", a custom kept from colonial times, signaling the closure of the city wall doors.