Alexamenos Graffito
The Alexamenos graffito is a piece of Roman graffiti originally carved into a wall of a building on the Palatine Hill in Rome, which is now a museum. It might actually be the earliest image showing the Crucifixion (of Jesus Christ). It’s estimated to have been made ~200 CE (Common Era). The graffiti shows a man worshipping a crucified, donkey-headed figure and contains the inscription: “Alexamenos worships [his] God.” (this obviously translated from the original Greek). It’s suggested the graffito was meant to mock a Christian man named Alexamenos.
Roman graffiti is actually very interesting (and can be pretty hilarious and lewd); I highly recommend checking out the source links on the citation page for more information about it.

Alexamenos Graffito
Exhibit Item at Palatine Museum (Rome)
Date of discovery: 1856
Site: Palatine Hill, Rome
Contemporary Technology: Graffiti

Graffiti is graffiti: art made without the consent of the ower of the object being graffitied. The practice hasn’t changed; the context is where the essence of graffiti has changed. In the Roman Empire, where graffiti was exceedingly popular and could be seen virtually everywhere, it was a form of widely accepted expression. Everyone in the empire graffitied for anything and no one really cared. Today, graffiti has a sort of “deviant” connotation to it, and many see it as a nuisance. There is still something to be said about the artist though (and they are artists, regardless of what the subject of the art is) and their way of expressing themselves through their graffiti artistry.