Rome is the only great European town that preserve the in fairly integral way city walls up to Roman epoch.

It is believed that the construction of most ancient city walls goes back to Servio Tullio (half of VI century b.C.). The perimeter of these it is not possible to reconstruct for how only sporadic tender tuff's squared blocks remain on the Campidoglio, on the Quirinale and the Viminale.
Certain instead is that the royal walls didn't arrest the offensive of the Galliums around the 390 b.C. who took the city and set it afire.

In the 378 b.C., during the republican age, a new surrounding walls made in tuff had been built with the height of ten meters, thickness of four and with a length of approximatively eleven kilometers; today named as Serviane Walls.
The parts better conserved can be found near the Termini Railway Station and along viale Aventino (Aventino Avenue).
The enclosed area was not entirely urbanized since the walls were constructed with mainly strategic purposes.

Later on, during the augustea age, the development of the city exceeded republican walls and the crisis of the III sec. pushed Aureliano to construct new walls.
The huge Aureliane Walls were finished in only four years (271-275); they were high 6-8 meters, with one thickness of about 3.50 meters; they had a length of 19 kilometri and their route was carried out on the imperial domain property, in order not to aquire other lands and therefore to weigh on state finances.
Such walls have been modified in the 401 from Onorio to adapt to the new techniques of siege.

The Roman Walls were restored many times until 1870. Towards the half of the XV century, in fact, they were restored under the supervision of the Alberti and, subsequently, Paul III decided to adapt the defensive structure to the developments of the war machines using gun powder.
In the centuries the degradation of many parts of the walls provoked various collapses. Through the ages the walls lost their military function and they became abandoned. Only in 1929 the first restoration works began.