Forte Malatesta is one of the most important and spectacular Renaissance fortified architectures in Italy and one of the most fascinating monumental sites in the city. The splendid fortress (recently restored), which bears the signature of Antonio da Sangallo the Younger, was definitively reopened in November 2010.

The fort, just outside the historic center, stands in defense of the left bank of the Castellano river: in pre-Roman and Roman times it was a bulwark that blocked access to the bridge. Destroyed and rebuilt several times, in 1349 Galeotto Malatesta , leader of the Ascoli militias in the war against Fermo, provided to reinforce it and it became a typical medieval fort which took the name of Forte Malatesta. Other destructions followed, until at the beginning of the 16th century, in the ruined fortress, a dodecagonal church dedicated to Santa Maria del Lago was built, still visible in the central body of the building.

However, it was Antonio da San Gallo the Younger in 1543, on behalf of Pope Paul III Farnese , who erected a new fort in the shape of an irregular star on that same site.

In 1828 the Fort was restored and used until 1978 as a judicial prison.

Since March 2014 it has housed the Museum of the Early Middle Ages which exhibits the precious items from the Longobard necropolis of Castel Trosino (6th – 8th century). Among the most important finds are the complete tombs of a lady (jewels, brooches, etc.) and a knight (sword, shield, horse harness, etc.).