Forte Sangallo overlooks the sea in the village of Nettuno and is one of the most significant examples of Renaissance military architecture in Lazio. Built just a short walk from the historic centre and the harbour, the fort still dominates the coastline today with its imposing defensive structure.

Construction of the fortification began in 1501 at the behest of Pope Alexander VI and his son Cesare Borgia, as part of a vast project to strengthen the coastal defences of the territories controlled by the Borgia family. At that time, Nettuno played a fundamental strategic role, being considered the ‘breadbasket of Lazio’ thanks to the fertility of the surrounding countryside.

The fort was designed according to the most modern military techniques of the time, inspired by models developed by the Sangallo family, from whom the structure takes its name. The fortress features a quadrangular layout with sturdy corner bastions equipped with characteristic ‘orecchioni’, thick walls sloping down to the water’s edge, and sophisticated covered artillery emplacements, designed to ensure effective defence against attacks from the sea.

One of the most interesting features of Forte Sangallo is its superimposed embrasures – openings used to position cannons – strategically placed between the curtain walls and bastions to protect the walls with grazing fire. At the centre of the complex stands a large keep, which was extended in later centuries.

After the fall of the Borgias, the fort came under the control of the Colonna family, before passing to the Apostolic Chamber and, in the 19th century, to the Borghese family. Over the course of its long history, it has also hosted important political events and illustrious figures. In 1925, the Treaty of Nettuno between Italy and Yugoslavia was signed here, whilst in 1931 the fortress welcomed Queen Marie of Romania and Princess Ileana.

Today, Forte Sangallo is owned by the municipality and serves as an important cultural centre for the town of Nettuno. Inside, it houses the Museum of the Allied Landing, dedicated to the events of the Second World War, the Antiquarium with archaeological finds, and numerous rooms used for exhibitions, events and conferences.

Its seaside location, imposing Renaissance architecture and rich history make Forte Sangallo one of the most fascinating attractions on the Lazio coast, capable of recounting centuries of military, political and cultural history.