250px|thumb|right|Ruinaulta from the Il Spir viewpoint
250px|thumb|right| Gravel banks and limestone cliffs on the floor of the Ruinaulta
Ruinaulta, also known as the Rhine Gorge, is a canyon in the canton of Graubünden (Grisons), Switzerland, carved by the Anterior Rhine between the villages of Ilanz/Glion and Reichenau. The gorge cuts through deposits of the prehistoric Flims rockslide, in which an estimated 8–9 cubic kilometres (1.9–2.2 cu mi) of rock collapsed from the Flimserstein and neighbouring peaks around 9,500 years ago, in what is considered the largest known landslide in the Alpine region.
The steep walls of the gorge are known locally as Ruinas, a term from the Romansh language meaning “pillar,” “gully,” or “scree slope”; aulta means “high.”