Flagy is an old fortified place. The village was built in the 12th century by order of Louis VII in 1130. On the edge of a royal domain, it is built according to a rectangular plan, as shown by the seven parallel streets leading to the river crossed by seven bridges or gateways. The course of the Orvanne has been diverted and developed to supply the village with water. The mill, built in the 13th century, still exists and is a good representation of the traditional regional architecture of the time.
Besides the river, seven wells, one in each of the parallel streets, provided drinking water. There are still several of them, which were used until 1960.
On Heritage Day, you can visit two underground entrances. A network of underground passages connected the food cellars which also served as refuges during invasions of the village by enemies. One can see in one of the underground passages some remains of ancient objects.
A curiosity on the roof of the church, the weather vane has two symbols: a rooster, the usual symbol, and a pig's head, another symbol, a lasting memory of a local legend, transmitted orally. During the Hundred Years War, the terrible Black Death reached many villages in Île-de-France. Affected by the epidemic, the inhabitants of a neighboring village came to seek help in Flagy, where there was a hospital (Hôtel-Dieu). But the Flagiens energetically refused entry into the village to the sick. The poor people had to look elsewhere for a better welcome. It is said that the bishop, outraged by this attitude of refusal, this lack of compassion, inflicted a punishment on the Flagians. Since then a weather vane in the shape of a pig's head has been turning according to the winds on the roof of the church.
Recently rediscovered in the "Favorite Village of the French" 2023, Flagy may not have won the crown, but remains a nice heritage to discover.