John the deacon has described them like an eye-witness, (l. iv. c. 83, 84;) and his description is illustrated by Angelo Rocca, a Roman antiquary, (St. Greg. Opera, tom. iv. p. 312 - 326;) who observes that some mosaics of the popes of the viith century are still preserved in the old churches of Rome, (p. 321 - 323) The same walls which represented Gregory's family are now decorated with the martyrdom of St. Andrew, the noble contest of Dominichino and Guido.