The Romanesque cathedral, dedicated to to St. Lawrence martyr, was consecrated in 1118 by Pope Gelasius II (modified later; restored 1934). It was built on the site of Roman ruins and the former church of the Twelve Apostles. The piazza, in absence of other public squares and centers of lay power, was the only city's public space for the whole Middle Ages. After the fire of 1296, provoked by fights between Guelphs and Ghibellines, the building was partly restored and partly rebuilt. Between 1307 and 1312 the façade was completed, the inner colonnades rebuilt with capitals and matronei added. In 1550 the Perugian architect Galeazzo Alessi was commissioned by the city magistrates to plan the reconstruction of the entire building; however, he executed only the covering of the nave and aisles, the pavement, the dome and the apse.