The basilica of San Lorenzo fuori le Mura (Saint Lawrence outside the Walls) as it is today is the combination of two distinct churches, one built in the sixth century AD and the other at the beginning of the thirteenth century AD around the tomb of Lorenzo, deacon of Spanish origin martyred under emperor Valerian and buried in the cemetery of Ciriaca along the Via Tiburtina. 

The church also keeps the relics of Santo Stefano (protomartyr) and for this reason it is from time immemorial one of the most worshipped in Rome, included within the restricted number of the five most ancient and important patriarchal basilicas. Constantine had already restored and adorned the tomb of San Lorenzo in the fourth century and built a large cemeterial basilica (basilica maior) in the surroundings. 

At the end of the sixth century pope Pelagius the Second built a new church with three naves and practicable galleries (matronea) the completely englobed the tomb (basilica minor). The ancient basilica maior was destroyed between the ninth and the twelfth century. 

Clement the Third (1084-1100) built the cloister and started fortifying the village (Laurentiopolis) that had developed around the basilica. Honorius the Third Savelli (1216-1227) gave the complex its current appearance building a new church that englobed the basilica built by Pelagius and transformed it into a presbytery inverting its orientation. Innocent the Fourth (1243-1254) raised the presbytery and commissioned the papal chair. 

Numerous restorations were performed in the course of centuries. The most radical one was performed in the nineteenth century by Virgilio Vespignani (1855-1864) was almost thoroughly cancelled by the rebuilding following the bombing in 1943, which tended to give the medieval appearance back to the church.

The brick facade with three arched windows was completely rebuilt after the bombings and is preceded by a portico attributed to the Vassalletto (around 1220), a family of  marble workers,  supported by six bare columns surmounted by a trabeation with a rich polychromatic frieze. 

The twelfth-century Romanesque bell-tower rises on the right behind the facade. The portico is decorated with end of the thirteenth century frescoes (Stories of St. Lawrence and St. Stephen and of Count Henry). Inside the portico two lions (that were already in the ancient vestibule) on the sides of the entrance portal and two sarchofagi on the right wall decorated with Stories of the Old and New Testament and Scenes of Vintage deserve to be mentioned. 

The interior with three naves reveals at first sight the non-homogeneous structure of the church with the two basilicas (the original one built by Pelagius and turned into a presbytery, and the one built by Honorius) adjacent, but not perfectly aligned. The twenty-two columns that divide the naves are different in size and marble, and perhaps come from the basilica maior. 

The counterfacade presents the Tomb of cardinal Enrico Fieschi, consisting of an early Christian  sarcophagus with a wedding scene and a canopy. The floor, the, ambos and the Easter candelabrum are Cosmati works (end of thirteenth century). 

The nineteenth century chapel of San Tarcisio by Vespignani opens at the end of the right nave and presents a beautiful Beheading of the Baptist by Giovanni Serodine (1619) of the school of Caravaggio. A chapel in baroque style with funerary monuments designed by Pietro da Cortona dedicated to Santa Ciriaca can be accessed from the end of the left nave. 

Two small stairways lead up to the presbytery, where the confession of San Lorenzo’s tomb is placed between four black and white columns. The presbytery is framed by pavonazzetto columns that support a magnificent trabeation with arm trophies and vegetable motifs (fourth century). 

The trabeation in turn supports the matroneum. At the centre of the Cosmati floor stands the ciborium, the most ancient work signed by Roman marble workers (1148), consisting of four porphyry shafts that support a pyramidal covering on small trabeated columns. 

The bishop’s chair is placed on the back wall (1254) and it is decorated with polychromatic mosaics and marbles, while the triumphal archis decorated with the famous mosaic dated back to the end of the sixth century representing Christ among the SaintsPaul, Stephen, Hippolytus, Peter, Lawrence, and pope Pelagius. 

The pope is represented in the act of offering Christ a model of the basilica minor. Pious the Ninth’s funerary chapel was built at the end of the nineteenth century reusing the narthex of the basilica built by Pelagius. It can be reached from the end of the side naves.