Towers may be either part of a fort or present as an isolated element or attached to the city walls themselves.
In the early middle ages and at the beginning of the civic feuds, towers constituted either an architectural element common to all feudal fortifications and castles, or an isolated element, functioning as observation and, mostly, as defense decks . They were usually square with limited inner space organized into various levels through wooden ladders, and sometimes were connected to underground niches used to preserve food in case of a siege.
In any case, the number of towers increased in the civic feuds shifting their role from mere defense to status symbol of the nobles; an increasing number of towers were built in the centres of the feudal towns according to an urban plan similar to the one belonging to the defense towers of the castles.
Gregorius states that in the 12th century Rome had 900 towers. Although this figure may appear exagerated,the city must have appeared full of towers, denoting the dwellings of the barons. The struggles among factions or those between the Pope and the Senate against the barons resulting in the confiscation and demolition of homes, towers and buildings of the losing part, were the main causes of the remarkable loss of these historical monuments, except for natural phenomena, as was the earthquake of 1348.
The towers throughout the Roman countryside were built in part to satisfy the need for defense and in part to identify the various districts. Some towers, called vigilae, were set within the fortified centres in the direction of the coastline functioning as signalling posts; this configuration already existed at the time of Gregorius the Great. Many of the towers disappeared while others, as that of Tor Vergata, is still visible, allowing to reconstruct the ancient network of districts, roads and defense systems.
Between the 10th and 11th century, Latium gained political relevance thanks to the aristocracy with its territorial jurisdiction within the province. They formed an alliance with the Pope to defend the towns and estates against the Saracens. A member of this new aristocratic militiae was Alberico, founder of the counts of Tuscolo lineage. In Europe, in the 11th century, the Papacy reacquired its prestige and thereafter, the abbeys reorganized the estates and proceded to gather the former rural populations into walled towns located in the areas which dominated the countryside called "incastellamenti". Feudal lords followed the example of the abbeys. As for the common people, the fortified castles secured their properties and provided a reference point. At the beginning, the fortified walled towns were useful to the Church as a form of defense but later on these towns became the very premise for passing on the power to the various lords.