Fragments of tile, potterys and amphora s were found to the west of the village and at a place called les Patots, a very old path was an old Roman road.

In the 12th century, the monks of Moissac built a castle on the left bank of the Garonne, facing the confluence of the Tarn, on the edge of the plateau which dominates the alluvial plain.

In an additional act to the charter, the Viscount of Lomagne swears to the monks and inhabitants of Saint-Nicolas never to take away their city or their castle and to protect them against invaders.

Abbot Bernard de Montaigu, who held the abbey chair of Moissac from 1260 to 1295, built the west wing of the castle and its two four-meter towers with heights of 25 and 28 metres.

The town plan is simple; it is a rectangle oriented east-west, 440 metres long by 200 wide, crossed by a main axis and surrounded by ramparts (now disappeared and replaced by boulevards) with in its center a vast square.