Domodossola is the most important locality of the Ossola valley. It has a Medieval centre called "la Motta". Its most interesting monuments are the Bishop's House (via Briona), the Tower of Briona, the Collegiate Church of Ss. Gervasio e Protasio, Palazzo Silva (near the Collegiate church) and Palazzo San Francesco (Piazza della Convenzione, 10). On the hill of Mattarella you can visit the Sacro Monte Calvario di Domodossola. Several valleys extend over Domodossola. First of all the Valle di Bognanco, famous for its spa. To the east you reach Val Vigezzo, whose most important centres are Santa Maria Maggiore, with a splendid parish church of the 17th century and the Rossetti Valentini Picture gallery and the skiing resort of Vigezzo.