The upper church of the Basilica di San Francesco was built after the Basilica Inferiore and consecrated in 1253, and the change in style and grandiosity is readily apparent. Its bright, airy interior is home to one of the world's most famous works of art, a 28-part fresco depicting the life of St Francis. For centuries, this extraordinary work has been attributed to Giotto and his pupils, but the question of its authorship is currently under debate in the art-history community.

　　The fresco starts just to the right of the altar and continues clockwise around the church. Above each image is a biblical fresco with 28 corresponding images from the Old and New Testaments (names of possible artists include Giotto and Pietro Cavallini). The frescoes in the basilica revolutionised art in the Western world. All the gold leaf and flat iconic images of the Byzantine and Romanesque periods were eschewed for natural backgrounds, people of all classes and a human, suffering Jesus. This was in keeping with Francis’ idea that the human body was ‘brother’ and the earth around him mother and sister.