St. Peter-Pagig is a former municipality in the district of Plessur in the Grisons , Switzerland . It was formed on 1 January 2008 through the merger of St. Peter and Pagig. On 1 January 2013 the former municipalities of St. Peter-Pagig, Calfreisen , Castiel, Langwies , Lüen , Molinis and Peist merged into the municipality of Arosa .