Blinnenhorn, Alpine summit in Lepontine Alps, Switzerland

Corno Cieco is a 3374-meter alpine summit in the Lepontine Alps on the border between Switzerland and Italy. The mountain has a northern subsidiary peak, Klein Blinnenhorn, standing at 3215 meters.

The mountain was first documented in 1881 when British painter and mountaineer Arthur Cust reached the summit in autumn. This ascent marked the beginning of Alpine exploration in this region.

The name Blinnenhorn is German, while Corno Cieco ("blind horn") is the Italian form used on the Formazza side; the Walser of Formazza call it z'Blinnänhorä. The summit sits on the main Alpine watershed, which changes direction exactly at the peak, turning from east-west to south-west toward the Blinnen pass.

The normal route starts in Italy from Rifugio Città di Busto (2480 m), climbs the Ghiacciaio dei Camosci and crosses the Gran sella del Gries to the summit, mostly on glacier, so watch for crevasses; rated F. A southern variant leaves Rifugio Claudio e Bruno (2710 m) and is now considered the normal route. From Switzerland, the route goes from the Passo della Novena past Lago Gries up the Gries Glacier, and depends on crevasse conditions.

The summit sits on the main Alpine watershed, which changes direction at the peak: the crest arrives from the east, bends northwest just before the top, then turns southwest toward the Blinnen pass. A secondary ridge descends southeast from just below the summit.