The 13th century Cosmatesque pavement was restored in the 18th century. Much of the original floor was replaced with marble tiles in grey and red. The area near the entrance is the most extensive survival, with a large grey granite roundel sawn from an ancient column and another one of porphyry. In the floor at the right side of the central nave is a slab enclosed within an iron balustrade, marking the spot where SS. John and Paul are said to have been decapitated.
(Additional photos of the floor here)