Ancient Mosaic in Pompeii Possibly the First-Ever ‘Beware of Dog’ Sign

Mosaic made of black and white tiles depicting a fierce looking guard dog with the words 'beware of dog' in Italian.

A mosaic depicting a guard dog was discovered at the entrance to the 'House of the Tragic Poet' amidst the ruins of Pompei by archelogist Antonio Bonucci in 1824. (Image: via Wikimedia Commons)