Castiel () is a former municipality in the district of Plessur in the canton of Graubünden in Switzerland. On 1 January 2013 the former municipalities of Castiel, Calfreisen, Langwies, Lüen, Molinis, Peist and St. Peter-Pagig merged into the municipality of Arosa.Nomenklaturen – Amtliches Gemeindeverzeichnis der Schweiz accessed 9 February 2013
