The tourist was seen by a guard allegedly carving the “enormous” letter on an interior wall of the ground floor of the famous amphitheatre, Il Giornale reported.
Rome’s archaeology superintendent, Mariarosaria Barbera, was quoted by the newspaper as saying that the damage to the monument is “notable” and had “removed part of the surface of the structure…compromising its preservation and image”.
The tourist is just the latest to be caught defacing the iconic monument.
In August, a 25-year-old Dutch man and a 26-year-old German woman were caught writing on the monument, while an Australian man and his son tried to leave their mark in January.
In March, a Canadian teenager also got into trouble with police after she was caught trying to steal a brick from the Colosseum, stashed away in her backpack.