The Altare della Patria in Rome houses Italy's "tomb of the unknown soldier," a type of monument that is usually hallowed and solemn ground.
But a couple of tourists who recently visited the memorial decided to strip down and bathe in the fountain in front of it.
Footage of the incident, published this week on an Italian blog's YouTube page, shows two men playfully wading into the fountain in their underwear. They pose for a few photos, and then one of them drops his pants completely, smiling and holding his fingers up in peace signs while his boxer shorts hang at his knees.
The video has apparently caught the attention of the Italian Government and Rome's local police, who are now looking for the men. Deputy Prime Minister Matteo Salvini of the far-right League party said on Twitter that he "will know how to educate these idiots if they are caught."
"Italy is not their home bathroom," he said.
In a statement posted on Facebook, Italian police said the behaviour was "illegal and outrageous," and that the perpetrators are not Italians, but "native English speakers." The police said they are investigating the incident and seeking assistance in finding the men.
Luca Bergamo, the deputy Mayor of Rome, said the tourists' decision to skinny-dip in the fountain "offends each of us, the memory of our country and the fallen, to whom the monument is dedicated," the BBC reported. "We are faced with a behaviour that denotes stupidity and ignorance, lack of respect for the history of Rome and Italy."
Bergamo added that the men "will get the maximum punishment possible" if they are caught. The Guardian reported that a police source said the fine could be at least US$460.
Rome's many fountains are often featured as the backdrop for films. In Federico Fellini's La Dolce Vita, for example, Swedish actress Anita Ekberg famously splashes through the Trevi Fountain.
That landmark was the scene of a different drama this summer, when an argument between two tourists jockeying for perfect selfie positioning led to a brawl between their two families. The Guardian reported that Rome implemented a new fine system last year for people caught eating by the fountain - or swimming in it.
It's not clear whether that fine included specific provisions for skinny dippers.