The Xith century fortifications built by Amaury I have an elongated shape from west to east. The walls are 80 cm thick, about 6 metres high and they are ringed by a moat.
The four gates, each being located at one of the four cardinal points, are connected together by high walls which protect Montfort L’ Amaury and its inhabitants. Several architectural remains can be found in some houses and terrace walls.
After being demolished during The Hundred Years’ War and the English invasion, they were eventually rebuilt after the wars of religion at the end of the XVIth century and after Charles IX’s promise to the inhabitants that he would grant its first charter to the village in return for rebuilding them.
As a consequence of the development of the village due to its prosperity under the influence of Anne of Brittany, the length of the wall had to be tripled thanks to the building of an enclosing wall which was slightly more than 60 cm thick.
Seven entrance gates to the village of Montfort L’Amaury were built :
Porte de la Tripière, Porte Bardoul, Porte de Brosse, Porte de Paris, Porte de la Minotte, Porte du Vivier et Porte de la Moutière.