The ruins are located on a high hill (125 metres high) and are composed of two walls from the 11th century flanked by a 15th century turret: in fact, remnants of the castle Anne of Brittany raised here. Guillaume of Hainaut, first count of Montfort, built a former castle in 996 and surrounded the city with big walls. The fief fell to Amaury, count of Montfort, a lord who gave his name to the city!
Here was born several great lords who played important parts in Middle-Ages wars, as for instance Simon de Montfort, who fought during the crusade against Cathars. In the 14th century, the county of Montfort fell to the duke of Brittany when Yolande, countess of Montfort, married duke Arthur.
Then the fief fell to the Crown of France. King Francis I gave it to André de Foix in 1537: he extended it and restored the castle. Then it fell to the d'Alençon and Luynes families. The fortress was sold during the French Revolution: the place was renamed Montfort-le-Brutus.