It is the main town square, known as “Platea Magna”, large square, in ancient times, in contrast with the “Platea Parva”, small square, i.e. the Cathedral Square. Near the intersection point between “Cardo” and “Decumano” (the Romans used these words to indicate the sense of town directions and divisions), this square was an important market place. It was almost totally surrounded by the 14th century arches. The “Broletto” and the noble Gothic small mansion of the “Diversi” look on to the square. There is also the desecrated church of S.ta Maria Gualtieri, founded in the 10th century. The imperial delegate Gualtiero wanted it to be built near his house. Today it is used as a centre for cultural events. Somewhere on the Square it is possible to get into the underground market, which was carried out in modern times.