This is the Carraresi wall; its colour transmits the warmth and varied shades of light, with its sky blue background and deep greens of the ancient rampart. In fact, the city appears to be encased in a setting which could almost be described as a "medieval shell". The city wall gives Montagnana an irregular form, almost pentagonal. It is about 2 km long and is surrounded by a large rampart which is between 20m and 45m wide. The eastern and west- ern sides of the wall are made from bricks which date back to the XIII century, the period of the Free City of Padua. The north and south sections, however, are made from composite material (various layers of trachyte from the Eu- ganean hills, bricks and calcareous stone). There are Guelph type merlons and the slits are positioned at various heights in order to strike the different targets. The 24 towers form a hexago- nal shape, they are between 17 – 19 metres high with a distance of about 50 metres between each one permitting an improved vision of the city perimeter. The towers at the 4 corners of the city are higher and stronger than the rest of the towers.