Monuments under attack
Two Californian tourists, age 21 and 25, were arrested by Italian authorities Saturday after allegedly carving their names in the upper level of Rome's Colosseum. A Russian tourist got a 4-month suspended sentence after trying a similar stunt in 2014.
Here's a look at other world monuments vandalized in recent years.
Nimrud demolished
The ancient Iraqi city of Nimrud, shown here in 2001, is also thought to have been destroyed by ISIS militants in recent weeks.
Sky-high graffiti
A high-climbing vandal sprayed Rio de Janeiro's famous Christ the Redeemer statue with gray paint in 2010. Rio's mayor called the act a "crime against the nation."
Bloody symbol
Protesters threw red paint on the Bandeiras monument in Sao Paulo in 2013. Members of Brazil's indigenous population reportedly led the attack, part of a demonstration against the country's treatment of Indian lands.
Hunting Fox
Protestors in Boca del Rio, Mexico toppled a statue of former President Vicente Fox in 2007, hours after it was placed by local authorities.
Exorcism by hammer?
In 2011, soldiers loyal to Ivory Coast presidential claimant Alassane Ouattara destroyed a "magic stone" monument they believed held an evil spell cast by supporters of rival Laurent Gbagbo.
Hateful symbols
Bulgarians gathered in 1995 to lay flowers at the local Anti-Fascist Monument after it was defaced with a swastika.
A king brought low
Tourists visiting Lisbon, Portugal, often stop at this memorial to King Joao I. The base of the statue was defaced in 2010, after investors downgraded the country's credit rating and citizens grew angry over lack of jobs.
Creative disobedience
A mystery artist painted over this Bulgarian tribute to Soviet Army soldiers in 2011, re-imagining them as U.S. comic book heroes and other pop culture staples.
ISIS attack
This 2005 photo shows the archaeological site of Hatra, northeast of Baghdad, in Iraq. This week, Iraq's minister of tourism and antiquities announced it would investigate reports that the Islamic State has leveled site.
Egyptian anger
A tribute to former Egyptian President Hosni Mubarak (left) underwent an ugly attack on the outskirts of Cairo in 2011. The memorial also depicts Nobel prize winner Ahmed Zewail, late president Anwar Sadat and novelist and Nobel Prize winner Naguib Mahfouz.
Ancient scribbling
The ancients were pioneers of rebellious writing. This detail, from a fresco in the Colosseum, shows graffiti thought to be from the Roman era. It was photographed in 2013.
Ruined temples
Another 2005 photo shows the temple to the Shamash sun god, also in Hatra. Iraqi officials this week blamed the international community for not acting sooner to protect sites such as Hatra against ISIS militants.
Toppling stones in Utah
This frame grab from a video shows two men cheering after a Boy Scouts leader knocked over an ancient Utah desert rock formation at Goblin Valley State Park in 2014. The vandals, Glenn Taylor and David Hall, pleaded guilty to misdemeanor charges to avoid jail time.
"Blood" of martyrs
In 2013, this new monument to Cairo's Arab Spring in Tahrir Square was splashed with red paint, representing those who died in related clashes.
No peace
"The Wall For Peace" near the Eiffel Tower in Paris was the site of this lone graffito. The word is "quenelle," a reference to controversial French comedian Dieudonne's trademark straight-arm salute.