Saint-Grégoire is a city of Ille-et-Vilaine, in the northern outskirts of Rennes, which it borders.
If its territory still includes 400 hectares of agricultural land and 70 hectares of green space, Saint-Grégoire benefited from the development of the Rennes area in terms of population, from 1500 inhabitants after WWII to nearly 9500 today as in terms of economic and commercial activity.
The city however maintained a framework of green and pleasant life, thanks to the Ille-et-Rance canal that runs through it and was already a popular place to promenade Rennais in the early twentieth century.
Nicknamed "Red City" because of the color of its ancient walls of Gallo-Roman origin, would Saint-Grégoire located on the Roman road Rennes-Avranches, and was then founded by a bishop of Rennes in reference to the cult of Saint Gregory the Great, pope in the sixth century.