Dog fresco uncovered on an ancient Roman food stand (thermopolium) in Pompeii, Italy. This painting may have served as a warning that a dog guarded the premises. Similar images have been found in mosaics set into the entrances of houses in Pompeii, known as cave canem (beware of the dog) mosaics. The bones of a dog were also uncovered on the premises, though it was a notably smaller breed than the one depicted in this fresco. Scratched onto the black frame above the dog is an insult directed at a man named Nicias, possibly a man of Greek origin. Thermopolia served hot food and drinks, especially to citizens without their own kitchens, which included much of the working and middle-classes. Pompeii was a Roman town with a population of around 20,000 that was destroyed when the volcano Mount Vesuvius erupted in 79 CE. Layers of ash have preserved the site, allowing archaeologists to glean much about life in the Roman Empire.