Two American tourists will be leaving Rome with a memento they weren’t expecting: a criminal record.

Security detained two young California women Saturday for carving their initials into a wall of the Colosseum — and then posing for a selfie to show off their handiwork, Italian newspapers reported.

The two women, ages 21 and 25, snuck away from the tour group they were traveling with and used a coin to etch the 8 centimeter high letters “J” and “N” into a wall on the west side of the Roman amphitheater.

Fellow tourists who spotted the vandals alerted security, who called the police.

The young women, whose names were not released, were cited for “aggravated damage to a building of historical and artistic interest,” according to Italian newspaper La Stampa.

Though signs against vandalism are posted all over the site in Italian and English, the girls said they didn’t realize that defacing a 2,085-year-old relic was that big a deal.

“We did not imagine it was something so serious,” they were quoted saying, adding that they will remember the rules “for a lifetime.”

They’ll likely remember the dent to their travel budget, too. Last year, a Russian tourist who carved his name into the Colosseum was slapped with a fine of 20,000 euros.

Authorities have recently upped security around the Roman ruins to thwart potential terrorist attacks, but more staff is needed to patrol for delinquent tourists – who tend to treat public ruins with less deference than other touristic hot spots like the Vatican, authorities said.

“Museums are treated like churches, sacred places where there are things of great value,” a spokesman for Rome’s archaeological sites told The Guardian. “Whereas the Colosseum is an incomplete building which has already been robbed.”