Why is it canonical?

Construction on the Basilica Church of Saint Francis of Assisi began soon after the canonization of Saint Francis, about two years after his death. It has since served as a major pilgrimage destination for those wishing to venerate the the saint whose work not only started the mendicant Franciscan order, but recast religious experience in a manner that deeply rooted religious experience as both personal and grounded in lived experience, especially experience with nature. It remains the center of the Franciscan order, and served as a locus of 14th century Italian artistic production.