Quite a few ancient g's have survived from the Roman era, and not just because of Vesuvius. :^) In one of the Bay of Naples towns' cat houses, someone wrote, "may I always and everywhere be as potent with women as I was here." Wonder how he did? :^)
One I read about was in Pompeii, outside the house of a local politician.
“HOC EGO CACAVI.” (Here I s*it.)