The Cathedral of San Gimignano is among the most important monuments in the town. The church has three naves with ribbed vaults punctuated by columns. The interior space, with a basilica-like floor plan, is punctuated by fourteen Tuscan stone columns, ten of which are round and four are octagonal.
The walls of the church are magnificent and entirely covered with frescoes, telling the story of the New and Old Testaments: observing them carefully us like reading the ancient book. The paintings are by painters from the 14th century Sienese school. On the wall to the right, there is a cycle of frescoes depicting the New Testament, by Lippo and Federico Memmi, while on the wall to the left, there are the stories of the Old Testament, painted in 1367 by Bartolo di Fredi. Inside the church, there are multicoloured decorations typical of medieval churches, such as the magnificent cross vault painted blue and the soffits of the arches that separate the naves, decorated with a band pattern typical of medieval Tuscan taste.
The Cathedral contains a Renaissance gem, the Chapel of Santa Fina, in which three very well-known Florentine artists worked together: Giuliano da Maiano as an architect, Benedetto da Maiano as a sculptor, and Domenico Ghirlandaio as a painter. The masterpiece is dedicated to the patron saint of San Gimignano, who was struck at a very young age by a serious illness and wanted to remain lying down for the rest of her days on a wooden board. At her death, the table blossomed with yellow violets. On the left, the fresco that celebrates the funeral of the young woman, with the town procession to pay homage to her and the towers in the background. Every year, in March, the Santa Fina's violets bloom between the towers that have made the outline of the medieval town famous. The church bell tower was also one of San Gimignano's numerous towers and, before the beginning of the 13th century, it was turned into a bell tower, opening large single-lancet windows in which the bells were placed. A door with wooden shutters opens up the view onto the cloister.