Black liquid was poured into the 18th-century fountain on Sunday
Activists from Ultima Generazione, which translates to Last Generation, staged the demonstration to protest the "inaction" of the country's government and institutions on climate change.
The liquid was diluted charcoal, according to reports.
In a statement, the group accused the government of continuing to invest in fossil fuels which are “the cause of the climate crisis that has hit Emilia Romagna and Marche in recent days, devastating the territory, claiming 14 lives, forcing 10,000 people to abandon their homes and leaving 28,000 others without light.” Police detained the activists about 20 minutes after their demonstration started. In the past, the group has hurled paint at Milan’s famed La Scala opera house, thrown food over the glass protecting famous paintings and sprayed orange paint on the facade of the Italian Senate.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...