The Duomo di Santa Maria Assunta anchors the lower end of Piazza del Duomo with a facade of brilliant gold mosaics that catch the morning light dramatically. The interior is Romanesque in plan but Baroque in much of its decoration; the apse frescoes by Filippo Lippi, depicting the life of the Virgin, are the highlight — rich in colour and remarkably well preserved for work painted in the 1460s.
Lippi was not the only great painter to work here. The chapel to the right of the entrance holds a Madonna and Child by the school of Pinturicchio, and a letter written by Saint Francis of Assisi is kept in the sacristy. The 12th-century facade's eight rose windows and the mosaic of Christ with Mary and John are worth studying before you go inside.