 The commune borders Gabiano to the north, Mombello Monferrato to the east, Castelletto Merli and Odalengo Piccolo to the south, and Odalengo Grande and Villamiroglio to the west.The two principal population centres are Valle Cerrina which had a population of 583 at the time of the 2001 census, and Cerrina itself, the historic centre and "capoluogo" which had a population of 353.Montalero (pop.