DescriptionBeware of the Dog! -- in Latin Cave Canem. This art is based on a mosaic of a guard dog on the floor of the entrance hall to the House of the Tragic Poet in the Roman city of Pompeii. Mosaics with fierce dogs guarding the entrance to homes were common for the rich of Pompeii. This particular mosaic shows an especially aggressive canine bearing its fangs, making it perfectly clear that intruders were not unwelcome.