Castle of Lettere, Medieval castle and military museum in Lettere, Italy

Castle of Lettere is a medieval fortification with four towers, including a tall keep and the Torre del Grano storage tower. The structure has a trapezoidal layout and now houses a military museum displaying archaeological finds from excavations.

Mansone I of Amalfi probably built the castle after the Amalfitans took Castrum Licterensis, guarding the duchy's border against attacks from the Gulf of Naples. The Normans added walls and a gate with drawbridge, and in 1263 the fief passed to Riccardo Filangieri, who built the keep and a tower. Under the Angevins it was enlarged with a south tower and gun emplacements; under the Aragonese it became a private residence, sold in 1529 to Isabella de Caprona.

The castle's name comes from Castrum Licterensis, the Amalfitan-held settlement it was built to guard. Inside the walls stood a church, houses and workshops, so the fortress was also a small inhabited centre. The Torre del Grano, lower than the other three towers, served as a grain store, and one tower still holds a masonry washbasin and several basins.

The site sits on a hilltop with good views of the surrounding area and is relatively easy to reach. Visitors should wear comfortable shoes since the ground is hilly and some sections have stairs.

From this location, visitors can see the port of Castellammare, the Sarno river mouth, and the Gulf of Naples. This strategic position allowed residents to watch trade routes and coastal activity.