In 1308 Bishop Enrico II gave 14 braccia at the east end of the church allowing them to construct the present day tribune and apse. During the 14th century it was decided to undertake a reconstruction of the entire church, work which intensified around 1374, executed by Florentine architects and finished in 1476. At that point the interior was re-embellished with works by Matteo and Vincenzo Civitali, Giambologna and Muzio Oddi. Of particular importance is the funerary monument to Ilaria del Carretto by Jacopo della Quercia (1408).