Pond of Montady, Medieval drained wetland in Hérault, France.

The Étang de Montady is a drained former freshwater wetland between Béziers and Narbonne, in Hérault. Sixty drainage ditches run from a central circular ditch called the Redondel out to the edges, dividing the land into wedge-shaped plots of pale tan and light brown, with green strips along some boundaries and a ring of trees around the rim. Water leaves through a gallery under the Ensérune hill and the Malpas tunnel.

In 1247, monks and landowners from Béziers received permission from the Archbishop of Narbonne to drain the brackish marsh. This drainage project transformed the unsuitable swamp into productive farmland over the following decades.

The name Montady comes from the Latin Mons Adius, and the drained land is still farmed in triangular plots. Since 1886 water from the Canal du Midi can flood the plots one by one, a practice used against phylloxera. The circular collector at the centre is called the Redondel.

The best view of the geometric field pattern is from the Oppidum d'Ensérune archaeological site, situated on higher ground overlooking the drained area. This elevated vantage point allows visitors to see the full radial design and understand the engineering work involved.

Water from this drained land flows through an underground tunnel beneath Malpas hill and eventually connects to the Canal du Midi. This hidden link joins the medieval drainage system to one of Europe's most famous waterways, built in the 1600s.