Abbaye de Sainte-Catherine du Mont de Semnoz, Medieval abbey ruins on Semnoz mountain, Annecy, France.

Abbaye de Sainte-Catherine du Mont de Semnoz is a ruined monastery situated in a secluded valley on Semnoz mountain near Annecy. The remains lie at around 630 meters elevation and are enclosed by dense forests and steep mountain slopes.

The monastery was founded between 1179 and 1228 by Marguerite de Genève and functioned as an active community for several centuries. In 1772 the residents abandoned the mountain location and relocated to the city of Annecy.

The abbey takes its name from Saint Catherine, and the valley and the path leading through it still carry the name Sainte-Catherine. Louise de Ballon, who lived here from the age of seven and made her solemn profession on 4 March 1607 at sixteen, left in 1622 and founded the reformed Bernardine order. The site later held a faience workshop run by Jean-Claude Burnod.

Access to the ruins follows a marked trail from the Vovray parking area, involving a 320-meter elevation gain over approximately three hours of hiking. The path is steep in places, so sturdy hiking shoes and adequate water are essential.

After closure, stones from the ruins were repurposed to help reconstruct the bell tower of Saint-Maurice church in Annecy below. This connection links the abandoned mountain site in an unexpected way to the modern city.