The church of San Paolo fuori la Mura, St Paul Outside the Walls, is one of Rome’s most important churches. The original church was very early indeed, founded, like St Peter’s, by the Emperor Constantine in the first quarter of the 4th century. That ancient basilica was mostly destroyed in a fire in 1823, thus requiring an almost total rebuilding. But many medieval portions remained or were heavily restored, including the magnificent mosaics by Pietro Cavallini from around 122o, which you see here.