Diagonal view across the chancel, depicting cosmatesque mosaics; The basilica of San Lorenzo fuori le Mura is one of the most important basilica churches and one of the Seven Pilgrim Churches of Rome. The basilica is the shrine tomb of the church's namesake, Saint Lawrence, one of the first seven deacons of Rome martyred in 258. Pope Pius IX, awaiting canonization into sainthood, is also buried at the basilica. Before the present-day basilica was constructed, the estate upon which it sits was once home to a small oratory built by Emperor Constantine I. The emperor built it over the site on which it was believed that Saint Lawrence was executed. In the 580s, Pope Pelagius II commissioned the construction of a church over the site, in honor o...