The village of Biran is an old Castelnau from the 13th century, located overhanging a limestone spur and which has preserved vestiges of ramparts and castle ruins.
Founded by a lord of the Biran family, it is entered through the tower gate which has served as a bell tower since 1666.
A single street opens onto the square where the Church of Our Lady of Pity stands, which contains a remarkable stone altarpiece (a masterpiece of 17th century Baroque Art).
To the south-west, on the double castle motte, was erected a fortified castle between 1080 and 1100, of which only one vestige remains today: the square watchtower and its 20 meters high.
The tourraque (word which designates a Gallo-Roman pile) of Lacouture is one of the best preserved of the department of Gers. Although without any particular decoration, its apparatus of small stones is almost intact. It is located on the right bank of the Baïse, in the middle of a cultivated field, a short distance from the road to Biran and towards the village of Brouilh-Monbert.
The presence of two Romanesque chapels on the right bank of the Baïse are also to be discovered: "Le Mas" and "Ramensan".
