Kropfenstein is a cave castle — a medieval fortification built inside a natural rock overhang on the cliff face above the Rhine gorge, in the neighbouring municipality of Waltensburg/Vuorz. It is one of the more unusual medieval sites in Graubünden, and the walk to reach it from Breil/Brigels passes through excellent mountain scenery.
The castle dates to the 13th or 14th century and controlled passage through the Rhine gorge below. The cave setting gave it natural protection on one side; the gorge made approach from below virtually impossible. The ruins are in reasonable condition given their age and position, and the views from the rock overhang are dramatic.