The Malatestiana Fortress is situated at the northern corner of Fano's Roman wall, which presumably embeds a tower. The structure was already in use in the 14th century and took the present form thanks to Sigismondo Pandolfo Malatesti and architect Matteo Nuti:  the works started in 1433, even though the fortress was actually built in 1438. The complex is a quadrangular plant with three sides, including the one where the entrance is, protected by a moat; according to archive documents the entrance was protected by raveline, a further fortification outside the moat, which is currently not visible and whose remains could be buried.
The fortress was designed following the "circles" defensive canons by Leon Battista Alberti: within the main fortification it was another defensive structure, the small fortress, which included the keep. The small fortress and the keep (the oldest parts of the Rocca) were also separated from the rest by a moat. The northern side of the city walls,  of the fortress, of the the rooftop and the doorknob coincide. In the 1500's, the east tower was enlarged, probably by Antonio da Sangallo, adding a mouth to the entrance door. The fortress was damaged in 1930 by an earthquake and was restored in the following years.
The small fortress and the keep were mined and destroyed by the Nazi troops fleeing in August 1944. Today inside the walls it is possible to visit the cells , the chapel and the rooms that housed the stables and the rooms used by the troops.