U.S. tourists arrested for carving initials into wall at Rome's Colosseum By Karla Cripps, CNN Updated 9:06 AM ET, Mon March 9, 2015 Rome's Colosseum is no stranger to vandalism. Last year, five tourists were caught carving graffiti on the historic amphitheater's walls. (CNN)Another one for the "tourists behaving badly" file. Two American women have reportedly been arrested for carving their initials into a wall with a coin inside Rome's Colosseum. Daily Italian newspaper La Stampa says the women, aged 21 and 25, were spotted carrying out the act by fellow tourists, who then told security. The two letters -- J and N -- were about eight inches in length and scratched on a brick wall at the historic Roman amphitheater. The women, both from California, reportedly snapped a selfie of themselves with their initials before they were arrested. Their names have not been released. The American pair may now face a fine for "aggravated damage" on a building of historical and artistic interest. If one Russian's experience is anything to go by, the price won't be cheap. Last November, authorities in Rome slapped a 20,000-euro ($21,685) penalty on a Russian tourist caught carving his name into the famed landmark. The 42-year-old man was apprehended after a guard at the Colosseum saw him carve the letter "K" in a section of brickwork. After police caught up with him, the man was found guilty of causing aggravated damage, fined and given a four-month suspended sentence. The Russian was one of five tourists caught carving graffiti on Colosseum walls in 2014. The earlier incidents involved two Australians -- a father and son -- and a Canadian and a Brazilian, both teenagers.