The town's origins are connected to the fact of erection of the defensive fortifications within the area and creating a place of a religious cult,so typical for the medieval times. Strategic location in the place where historical lands - Anjou and Maine - converge with the Brittany's border, contributed to the city's localization.

The only inhabited place on the right bank of the Mayenne river in those times, was Domaine de Bazouges (name comes from the term "basilica"), the place of religious cult, probably set up by the end of IV century by Saint Martin, the bishop of Tours. By the end of IX century, the place was destroyed by the Norman Conquest and about the 10th century a local count gave it to the Benedictine abbey Saint-Aubin.

Later, with the Benedictines' permission, the count built a small fort and a fortified tower within the aforementioned location. An officer named Gontier was appointed for the administrator of that place.

A bustling town gradually developed. In the 13th century, it was surrounded by city walls 2400 m long and accessible via four fortified gates. Soon, the Saint-Aubin's monks established a monastery next to the fortress. Spinning, canvass weaving, tanning and intensive transport between Laval and Agers cities contributed to the economic development of the town.

Today, having existed for almost 1000 years, Château-Gontier town, with about 11 000 citizens, is divided into two parts by the Mayenne river, the right bank of which borders the Northern side of the city (Haute Ville), and the left one - the outskirts (Faubourg).

These two parts are connected by the Saint-Julien bridge and the so-called European Bridge. In 1990, the Château-Gontier-Bazouges municipality was established. Its name refers to the aforementioned Domaine de Bazouges.ontier.fr