The current interior has a nave with two aisles divided by four pilasters and eighteen ancient columns.
The main altar is a red granite piece also dates from the 12th Century and the fabulous Easter candelabrum from the 13th Century.
In the sacristy there is a precious 8th-century mosaic fragment brought here from the Old St Peterĺs Basilica.
The church contains, located in its porch, an ancient sculpture entitled "La Bocca della Verita", "Mouth of Truth". Its name and popularity derive from a medieval legend that if a liar placed his hand in its mouth, it would be bitten off.
Its bell tower is the tallest medieval belfry in Rome.