Cirque du Fer-à-Cheval, Natural limestone cirque in Sixt-Fer-à-Cheval, France.

The Cirque du Fer-à-Cheval is a natural limestone cirque in Sixt-Fer-à-Cheval, Haute-Savoie, forming a 4 to 5 km semicircle of cliffs 500 to 700 m high. Its pale grey and tan walls, banded and streaked dark by water, are crowned by summits close to 3,000 m, among them the pic de Tenneverge (2,989 m), the Cheval Blanc (2,831 m) and the Grenier de Commune (2,775 m).

The cirque is cut into Jurassic limestone, rock that is heavily fissured and prone to collapse. A landslide from the Tête Noire in 1602 buried several hamlets of the cirque, and a commemorative chapel stands in the middle of the cirque today. Further collapses occurred in 2003 in the Nant des Pères sector and on 6 September 2025 at the Pas Noir, near the Méridienne waterfall.

The name comes from the horseshoe (fer à cheval) shape of the limestone wall. A chapel stands in the middle of the cirque, recalling the 1602 collapse of the Tête Noire that buried several hamlets. The cirque lies within the Sixt-Passy National Nature Reserve and is part of the Grand Site de France network.

The cirque lies at the end of the Giffre valley road from Sixt-Fer-à-Cheval, and the valley floor is reached by flat paths from the car parks. The waterfalls are fed by snowmelt and reach their peak in June. The site is part of the Sixt-Passy national nature reserve, and rockfalls have occurred, including one in 2003 in the Nant des Pères sector.

The 1602 collapse of the Tête Noire buried several hamlets of the cirque; a commemorative chapel stands in the middle of the valley floor. More recently, about 300,000 m³ of rock fell in the Nant des Pères sector in 2003, and roughly 35,000 m³ came down at Pas Noir near the cascade de la Méridienne on 6 September 2025.