The village is situated in Friuli, close to the borders with the Province of Belluno, Veneto.

Linked with a street to the National Road 251, it is 3 km from Erto, 4 from Castellavazzo and 5 from Longarone.

The colloquial language spoken in Casso is the bellunese, a Venetian dialect.

Situated upon the Vajont Dam, Casso was one of the villages involved in the disaster of October 9, 1963.

Partly damaged as Erto, the village was evacuated and in 1971 its population was transferred in Vajont, a new municipality built near Maniago.