It's impossible to miss this enormous Mannerist-style church, dominating the valley below Assisi. Constructed between 1569 and 1679 to preserve the 9th-century chapel known as Porziuncola, where St. Francis established his order in 1209 (Benedictine monks gifted the chapel to him), it also contains the Cappella del Transito (where Francis died in 1226), and the Cappella delle Rose, on the site of the saint's former mud hut. The basilica tends to be visited by bus loads of Catholic pilgrims rather than tourists, but the altar screen of Prete Ilario da Viterbo (1393) in the Porziuncola is definitely worth a peek even for non-believers, and the sheer monumental aspect to the place is certainly awe-inspiring.

The Museo della Porziuncola (Tues-Sun 9:30am-12:30pm and 3-6pm, 7pm in summer) chronicles the history of the site and the church, and displays works by Cimabue, Pisano, and Andrea della Robbia.