It has been called one of the most beautiful city squares in the world, is undoubtedly one of the most characteristic and polychrome: its dramatic effect goes hand in to the color of the buildings that surround it, to their architectural line exalted by three sequences porches built between the fifteenth and sixteenth century. Today is the heart of historical center, but in the past was offset from the walls. It is characterized by the presence of monumental Fountain of Neptune, on designed by sculptor Francesco Antonio Giongo between 1767 and 1769, as evidenced by license plate.