Rocca di Urbisaglia The Rocca di Urbisaglia is a 16th - century military fortification , including ruins of medieval fortifications and Roman walls . Its imposing position , dominating the urban area and the Fiastra Valley below , suggests that the Arx ( the citadel , the most protected area of the town ) or the Capitol of the Roman town Urbs Salvia was once located here . History . The population of " Urbs Salvia " took refuge all around the Arx - Capitolium stronghold after leaving the town , because of the Barbarian invasions . Here the " Castro de Orbesallia " , ruled by the Abbracciamonte family , had its origins . During the 13th century , several members of the Abbracciamontes started to sell their part of Urbisaglia to the comune of Tolentino , who soon became the only owner of the town . To prevent any rebellious acts from the citizens of Urbisaglia , who resented the external power over them , Tolentino asked the pope Alexander VI the permission to build a new fortress , which was already finished in 1507 , when a 12 soldiers garrison was sent to guard the town . Structure . It has a trapezoidal shape with the longest side facing away from the town in order to better face potential attacks . There are four corner towers , a gate tower and a keep where the garrison Tolentino had imposed on Urbisaglia resided . Keep . It was originally a watchtower . It has undergone several reconstructions between the 12th and 15th centuries and its current height ( 24 m / 79 ft ) is lower than it was initially . The top , currently crowned with Ghibelline merlon s , was covered with a gable roof . The entrance to the keep was at a higher level than the ground , so that the only way to enter it was through a wooden ladder which could be removed in case of danger . Gate Tower . It was protected by the North tower and the keep and had its own musket embrasure s . It once joined the fortress and the Western wall , later destroyed . The entrance to the fortress was located at a higher level than the ground and could be reached through a wooden ladder which was removed in case of danger . Current entrance was a small door opening toward the outside of the fortress . It later became the only viable entrance after the anachronistic wooden ladder was destroyed . West Tower . Along with the South Tower and the curtain wall connecting them , it was the external front of the fortress . It had two fire levels , the first one on the gun emplacement at the top , which was protected by merlon s and embrasure s , and the second one at ground level in the casemate with a reconstructed barrel vaulted ceiling and three embrasures . South Tower . Facing enemy territory , it was the fortified tower with the highest exposure to risk . Similarly to the West Tower , it has two fire levels . Roman remains from Urbs Salvia are still visible at its base . East Tower . Located within the walls of the fortress , the function of this tower was not to defend but rather to store provisions and supplies . In case of a siege it was used as living quarters : that ' s the reason why , unlike the other ones , the East tower is covered with a gable roof . It is also the only tower where the groined vault has remained intact . By the embrasure s below the vault , there are vent - holes whose function was to let out smoke and gases produced by artillery discharge . North Tower . Enclosed within the fortress ' s walls , its function , unlike the East Tower , was to defend the North - eastern front in case attackers were to break into the city walls and spread throughout the castle . There are three embrasure s at ground level , while the vault which used to cover the chamber is no longer present . Cistern . It was built to catch and store rainwater which was then used for the daily needs of the fortress occupants .