Bristol man Ivan Danailov Dimitrov, 27, etched “Ivan + Hayley 23” into one of the walls of the nearly 2,000-year-old monument using a key, the BBC reports.

He is now facing a criminal investigation and could be fined up to €15,000 (around £12,500) and/or imprisoned for between two and five years.

In a letter of apology sent to Roman authorities, including the local prosecutor’s office, Mr Dimitrov said: “I admit with deepest embarrassment that it was only after what regrettably happened that I learned of the monument’s antiquity.”

Alexandro Maria Tirelli, his lawyer, has said he is is seeking a plea bargain with local prosecutors.

“The boy will certainly benefit from a suspended sentence,” he said. “The fact is heinous but not serious.”

The Colosseum was built from 72 to 80 AD and attracts millions of visitors every year. It is the largest amphitheatre built during the Roman Empire and is famous for the gladiator battles it hosted for centuries.