The Basilica is the great religious-art monument of Umbria, two churches stacked on a single hillside above the town. The Lower Church, dim and low-vaulted, holds frescoes by Cimabue, Pietro Lorenzetti, and Simone Martini — the Martini cycle of St. Martin in the south transept chapel is one of the finest fresco cycles in Italy. Below it, in the crypt, is the tomb of St. Francis himself, the focus of a quiet, constant pilgrim traffic.
The Upper Church above is bright and Gothic, and famously holds the cycle of 28 frescoes on the life of St. Francis, traditionally attributed to Giotto and his workshop — among the founding works of European narrative painting. The 1997 earthquakes brought down parts of the ceiling and killed four people; what you see today is the result of a careful restoration. Dress modestly (no shorts, no bare shoulders), arrive early or late to avoid coach groups, and allow at least 90 minutes for both churches.