Forte di Vigliena, 18th-century fortress in San Giovanni a Teduccio, Naples, Italy

Forte di Vigliena is a pentagonal fortress built in tuff, only six metres high to keep it defiladed from naval fire, with two front sides each up to 35.9 metres long. A nine-metre-wide, five-metre-deep moat surrounds it, and access was through a triangular ravelin with a parapet and guard loophole. Inside were a well and casemates for a refectory, weapons workshop and tool store.

The fortress was built in the 18th century as a defensive installation to protect Naples Bay from seaborne attacks. During the political turmoil of 1799, it became the site of a devastating explosion that transformed its role.

The fort's name comes from Juan Manuel Fernández Pacheco, Marquis of Villena, the viceroy who had it built in 1702. Under the Kingdom of the Two Sicilies, cadets of the Nunziatella military academy practised artillery here. Alexandre Dumas, in his essay on the Bourbons of Naples, described the 1799 explosion, and the site is still not open to visitors.

The fortress is currently closed to visitors and undergoing restoration work. Those interested in viewing it can explore the surrounding area and observe its structure from nearby streets.

A water well in the central courtyard provided essential supplies, while workshops enabled repairs of weapons and equipment inside the fortress. These practical facilities reveal how the installation was designed for long-term occupation.