We tend to forget the damage the Second World War caused to some churches. Here is what the facade looked like prior to July 16, 1943:
From Blessed Ildefonso's The Sacramentary:
The Laurentian basilica owes its foundation to Constantine, but being considered too small, a large upper aula was added to it by Pelagius II (578-90) and dedicated to the Blessed Virgin.
From the Churches of Rome wiki:
The first church was built in the 4th century over the tomb of St Lawrence. This was done by digging into the catacomb he was buried in and isolating his shrine so that a church could be built around it.
It was restored by Pope Pelagius II (579-590). This church has been preserved as part of the present church; it is the part beyond the altar.
Pope Honorius III expanded the church by connecting a 5th century church (built by Pope Sixtus III and dedicated to Our Lady) to San Lorenzo. The old church became a new choir and sanctuary. This placed the high altar with the tomb of St Lawrence in the middle of the church. The orientation of the church was reversed. It can clearly be seen that the two parts do not align perfectly; this is because the basic structure of the 5th century church of Our Lady stood has a slightly different orientation, and rather than demolish it the architect decided to work within the existing walls.
Blessed Pope Pius IX (1846-1878) had Virginio Vespagniani restore the church. Most of the Baroque additions were removed at this time.
The church was damaged during the 2nd World War...
The confessio is below the high altar, and can be entered from the nave. Here, St Lawrence and St Stephen are enshrined. The latter was brought here from Constantinople by Pope Pelagius II when he restored the church. On the sides of the entrance to the confessio, there are steps that will take you to the oldest part of the church.
[...]
Looking from the choir back towards the entrance, the arch in the oldest part has 6th century mosaics, made during Pope Pelagius II's restoration. The Pope is depicted without a halo, holding a model of the church. The other persons are Sts Lawrence and Stephen, the Apostles Peter and Paul and the Roman martyr St Hippolytus. Only the figures of St Lawrence and Pope Pelagius II are in their original state; the others are the results of later restorations.
Beneath the floor of the choir is the original floor level of the first church...
The entrance to two catacombs, those of Cyriaca and Hippolytus, is in the left aisle.
