XIth century

At that time, the island of Saint Cosme (in the course of the Loire) already had a fishery, providing the monks of Saint Martin of Tours with fresh fish.

Between 1001 and 1022, Hervé de Buzançais, treasurer of Saint Martin, decided to set up a monastery demonstrated by the remains of the small church of the year one thousand discovered during the archaeological digs of 2009.

The presence of the relics of Saints Cosme and Damien in Tours could lead to the origin of the place's name, however no text confirms this.

The monastery was rented to 12 priests from the Abbey of Marmoutier in Tours until 1075.

The famous Berengar of Tours, at odds with the Church because of his view on the Eucharist, moved to Saint Cosme after 1060 or 1079 with a few canons. He died here in 1088.