Beware of Dog—In Mosaic
Step over the threshold of a Roman villa, and a fierce dog stares up at you—from the floor.

Unknown — "Marble relief fragment with gladiators" (1st–3rd century CE), public domain
Guard Dog in Stone, Not Flesh
Step through the wide door of a Pompeian villa, and a mosaic dog growls up from the tiles. Black and white, jaws bared, the warning is clear—thieves beware.
Home Security, Roman-Style
Romans didn’t just keep real guard dogs. They set anti-theft mosaics—'Cave Canem', Latin for 'Beware of the Dog'—in their doorways. Archaeologists have uncovered more than a dozen in Pompeii alone, each one a silent, permanent watchdog.
Romans set warning signs into their floors, not their doors. Archaeologists have found dozens of 'Cave Canem' mosaics—'Beware of the Dog'—laid right in the entrance halls of Pompeian homes. Sometimes the dog is chained, fangs bared. Sometimes it's just the words, set in black and white tesserae for every visitor—and would-be thief—to see.