The history of the Louvre begins around 1190 with Philippe Auguste’s decision to erect a fortified enclosure to protect Paris. This was an important gesture in favor of urbanism and a display of the king’s authority just as he was preparing to leave the country to go to war in the Crusades. To defend one of the weak spots in this fortification, namely its junction with the Seine, a castle was needed: as such, the Louvre was born. The building designed by Philippe Auguste’s engineers was square in plan, protected by a moat, and equipped with circular defensive towers at its corners and in the middle of its sides. In the center of its courtyard stood a main tower with its own moat. This model was used on several occasions with some variations; the Château de Dourdan in Ile-de-France still offers a well-preserved example.