The ancient walls of Pisa were built in 1155, with an average height of 11 meters. In addition to the walls, several towers were built, some of them have remained unchanged, such as the Tower of Santa Maria, the Lion Tower, the Tower of St. Agnes.
The whole thing was a real obstacle to the enemy. The Medici, in the sixteenth century did restore the walls also building a fortress adapted to new military techniques. During the Second World War, part of the walls were damaged and demolished. And this is the case in the San Paolo a Ripa d'Arno.