Sanctuaire de Mars Mullo, Gallo-Roman sanctuary in Allonnes, France

The Sanctuaire de Mars Mullo, also called the Tour aux Fées, stands in a wood between the HLM housing estates of Allonnes and the Sarthe. On a hill above the river are the remains of a hexagonal building, beneath which traces of a Gallic sanctuary were found, extended by a Roman-style entrance and enclosed by a wall.

The site was occupied from protohistory to the 4th century AD, with a Gallic sanctuary later replaced by a hexagonal building and a Roman-style entrance within an enclosure. In 1953 Jean-Noël Térouanne saw what looked like a wall after a storm uprooted a tree; his father Pierre, an archaeology enthusiast, began the first excavations. A CNRS/ENS team resumed digging in 1993, and the site was classified as a monument historique on 6 November 1961.

The place served as a gathering point for communal worship and spiritual observance among the local population, as revealed through excavated artifacts. The physical layout and objects found here show how people expressed their beliefs and conducted rituals in daily religious life.

The site is open to visitors on foot, and comfortable walking shoes are recommended since the ground is uneven. Guided tours are available for groups and provide better understanding of what you are seeing among the ruins.

The sanctuary is also called the Tour aux Fées, after a legend that a Roman of Alauna locked his daughter Bella in a tower to protect her from a snake; she died from a viper hidden in a basket of grapes and was buried beneath it. Witnesses were said to see her ghost singing Roman songs on the ruins.