The fortress dates back to the 14th century and it is located in a vast grassy clearing, named Piazzale Giovanni dale Bande Nere. Its present aspect is the result of the works carried out by the architect Dainesio Maineri in 1440. He transformed the four square towers into round towers for defence purposes. 
The square layout fortress was surrounded by a large moat, which is still visible on three sides. You can also see the two ravelins, connected to the entrance doors by a drawbridge. Along the centuries, the fortress fell under the control of the families who ruled over Imola. In 1473, it became a possession of the Riario-Sforza lordship, namely Girolamo Riario and his wife Caterina Sforza. 
The visit starts in the underground "Springalds Room", which hosts a collection of springalds, falcons and falconets dating back to the 15th and 16th century. The southeastern tower features the Riario-Sforza embrasures. Another room contains a wide range of 18th century rifles and muskets while the "Captain Apartment" displays armours, helmets and weapons dating from the 14th to the 18th century. 
After the Chapel of St. Barbara, the visit continues along the patrol trenches on the glacis equipped with round loopholes for bombards, trap-doors/machicolations and swallow-tailed merlons. 
The visit leads from the northeastern to the northwestern tower and offers a global view of the main courtyard and of the so-called "Paradiso" (heaven), a noble residence with an elegant portico. The south-eastern tower houses a collection of 16th century ceramics found during the restoration works carried out in the fortress.