The remarkable Piazza del Duomo is like a great open-air theatre and its wings are represented by the high medieval walls that still today enclose and protect the monuments, creating a unique scene.
Historical sources confirm that the construction of the walls began precisely in this part of the town in 1155, during the consulate of Cocco Griffi. There are two reasons for this choice.
The first is connected to the increase in importance of the Episcopal area: the enlargement of the cathedral, symbol of the cultural revival of Pisa, was almost finished, the construction of the baptistery had begun and there was already a project for the bell tower, the famous leaning tower.
The other is a military reason: in fact, from this corner of the town, through the bridge over the Auser (the river that flanked the northern part of the square), entered the trading route that connected Pisa with Liguria and with France, and that was a possible way in for the enemy armies.
The construction of the walls took two centuries, at the end of which the circle of walls extended for 7 kilometres, with an average height of 11 meters and a width of 2 meters. They represent the period of greatest urban development of Pisa, began with the boost of economic welfare produced by the intense sea trade and that determined the extension of the town beyond the inner early-medieval walls.
The first part of the walls was built with rusticated ashlars from Livorno (cemented sand extracted near Livorno), and went from the north-western corner, from the tower of Santa Maria (also called tower of the Auser), to the close tower of the Lion, so-called for the great marble sculpture that still today surmounts the gate. This part was built in just a few years. On the other hand, the rest of the walls were built in various phases, as confirmed by the different materials used.
The Tower of Santa Maria was of fundamental strategic importance, controlling the entrance to the bridge below. It was heightened by using a different material (sedimentary breccia from Asciano), also used from 1261 to heighten the rest of the walls. The tower was connected to the walkway on the walls through two narrow portals.
In 1499, during the terrible Florentine siege, this tower, like all the others, was reduced to the height of the walls, and it was built higher again only during the mid-19th century, when also the crowning brick merlons were added.
The visit to this tower allows an enchanting view from above on one of the most remarkable squares in the world.
Comune di Pisa