Tiefencastel (Romansh: Casti) is a village and a former municipality in the district of Albula in the canton of Graubünden in Switzerland . On 1 January 2015 the former municipalities of Alvaschein , Mon, Stierva , Tiefencastel, Alvaneu , Brienz/Brinzauls and Surava merged to form the new municipality of Albula/Alvra .

Tiefencastel is first mentioned in 831 as in Castello Impitinis. Starting around in the 14th century it was known as Tüffenkasten.

Before the merger, Tiefencastel had a total area of 14.9 km2 (5.8 sq mi). Of this area, 20.3% is used for agricultural purposes, while 49.6% is forested.