Built near the mouth of the Petit-Rhône, the Church of the Saintes Maries de la Mer held an important strategic position, because at the time of its construction, between the 9th and the 12th centuries, pirates were attacking  the coast and it was necessary to defend it against  invasions.

The church towers over the village and is  visible from as far as 10 km inland.  It is a true fortress formed of a single, straight, unadorned nave  50 feet high . The roof is encircled by a rampart walk, with battlements and machicolations, and served as a watchtower. The choir and the apse are surmounted  by  a semicircular keep housing the former guards’ room  known as the “upper chapel ".  Lookout  slits pierce the walls at regular intervals.  The church also served  as a refuge for the inhabitants of the city, and there was even a fresh-water well inside. Today, the statue of St. Sara, a major figure of the Gypsy cultural tradition, is in the crypt, to the right of the altar.  One can also see  a pagan altar from the 4th century B.C. in the church.