This article originally appeared on Travel + Leisure.
The Trevi fountain in Rome has had a longstanding tradition: if you stand with your back to the fountain and toss a coin over your left shoulder you are guaranteed a return trip to Rome. Each day thousands of people partake in the custom, which equates to approximately $15,000 a week and almost $1 million a year in collected coins.
There’s so much build-up, that each day the Roman Catholic charity Caritas takes an hour to sweep the fountain and distributes the money to the needy. They even opened a low-cost supermarket in 2008 from the collection.
While the Trevi fountain needs to be cleaned every day, other famous fountains collect their loot every few months. The lake at Las Vegas’ Bellagio, for example, makes about $12,000 a year, and uses a very efficient cleaning system. A giant vacuum is used to remove everything from the floor of the lake.
Similarly, the fountains at the Mall of America in Minnesota make about $2,000 a month, which is donated to charities and nonprofits. The fountains at all 24 Rainforest Cafes make about $25,000 a year, which is donated to environmental charities. And the fountains in Disney World raised $18,000 in 2014, all of which was donated to children in foster care.
Other interesting fountain intel: The 9/11 Memorial has collected almost $3,000 in change, despite the fact that people are not allowed to toss coins. The fountain at Bryant Park, meanwhile, collects about $3,400 a year, which pretty much just pays for the coin collectors.