First built in a pure Provencal Romanesque style in the 12th century, it was rebuilt in 1425, it is a marvel of stacked arches with a strong Byzantine flavour and is topped nowadays with a gargantuan Virgin Mary lantern - a 19th-century afterthought - that glows for miles around. The Baroque styling in the nave dates from 1670. Tha i''s the tomb of Pope John XXII in the center-left chapel.