Castillo de San Julián

Spain built this fort around a tower its own enemy had constructed. When British forces captured Cartagena in 1706, they built a defensive tower on this hilltop — and when Spain retook the city, rather than tear the tower down, its engineers simply built an entire fortress around it.

A fortress that took nearly 120 years to finish

During the War of the Spanish Succession, British Admiral John Leake occupied Cartagena in 1706 and built a cylindrical tower on Monte de San Julián, capable of housing twenty men along with storage and water cisterns. Once Spain regained control, King Charles III ordered a proper fort built here, incorporating the captured British tower into its design rather than replacing it — but the project moved with genuine, almost comic slowness. Ground preparation began in 1771; actual construction didn’t start until 1861; the fort wasn’t finished until somewhere between 1883 and 1888, roughly 117 years after it was first proposed. It was, notably, the last of Cartagena’s four major hilltop forts to be completed, built a full century after its counterparts at Galeras, Atalaya and Moros.

From coastal defence to officers’ prison to phone mast

San Julián’s actual military purpose barely outlasted its construction. It served as a working coastal battery until being decommissioned in 1947, but its most notable later role came earlier: during the Spanish Civil War, the fort was converted into a military prison specifically for high-ranking Spanish army officers. Today, ownership has shifted again in an almost absurd direction — the fort belongs to Telefónica, Spain’s national telecommunications company, which has installed modern antennas within the historic structure. The site remains freely accessible and structurally intact but genuinely dilapidated, its courtyards and walls open to walk but its interior buildings closed off, while Cartagena’s city administration works toward eventually reclaiming and restoring it.

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