The defense of Gubbio originally involved three fortresses:

1. ✴the so-called Cassero Grande, just outside Porta Sant’ Ubaldo; and
   

2. ✴two other fortresses on the top of Monte Ingino:
   

3. •Rocca Posteriore, which controlled the gorge of the Camignano; and
   

4. •Rocca Anteriore, which looks down on the city and the plain beyond it, the likely direction of attack from, for example, Perugia.
   

These structures should probably be seen in the context of the rebuilding of the city walls by St Ubaldus in ca. 1160.  They certainly existed in 1190, when they were mentions in the privilege granted to Gubbio by the Emperor Henry VI.

Cassero Grande

The medieval fortress outside Porta Sant’ Ubaldo was rebuilt in ca. 1480 by Duke Federico II and completed during the regency of Ottaviano Ubaldini.  Its construction required the demolition of the adjacent Monastero di Sant’Agnese in Monte and the closure of the adjacent Porta Sant‘ Agnese (the possible site of the Ikuvine Porta Trebulana).

The fortress was largely demolished in 1502.

Fortresses on Monte Ingino

The remains of Rocca Posteriore stand on a steep limestone ridge at the summit,  with traces of Rocca Anteriore close by.  An anti-Imperial faction expelled the supporters of the Emperor Henry VI in 1190 and destroyed them, lest they should fall into Imperial hands.  They seem to have been rebuilt by 1194, when the relics of St Ubaldus were translated from the old Duomo to a nearby oratory that was dedicated to the Milanese SS Gervasio and Protasio.   (This was later to become the site of Basilica di Sant’ Ubaldo).  It is likely that this site was chosen so that the soldiers stationed here could protect them.

Rocca Posteriore was destroyed again in 1383 but was partly restored in the middle of the 15th century.  It is now largely in ruins, although one of its towers has been rebuilt.

Only scant traces of Rocca Anteriore survive.