Every department store in Germany used to have a paternoster, says Patrick Carr of the Elevator History Museum. But that was the late 1960s, and now the idea of a passenger standing by an open elevator shaft and hopping into a box at exactly the right moment sounds risky. Today, these oddly-designed lifts are fading from European cities, and soon travelers might not have a chance to ride them any longer. But what exactly is this scary-sounding contraption?

The paternoster, pictured above, consists of two elevator shafts side-by-side, with no doors. Within them, a chain of compartments—also without doors—moves continuously on an endless belt, like a weirdly efficient Ferris wheel. In one open shaft the compartments go up, and in the other they come back down. If a person stays in their small cabinet after the last floor of a building, they may fear certain death, or think they’ll be turned upside down, but the box they’re standing in just keeps going up or down and around again, like a Ferris wheel, plunging them briefly into darkness until they again reach an open floor.

This odd elevator was once somewhat common. It was invented in the 1860s by Peter Ellis, an architect from Liverpool. Carr has documented well over a hundred paternosters, mostly in Germany, some of which still exist and some of which have likely closed. As of 2006, there were about 70 paternosters in the Czech Republic, according to a Radio Praha segment from that year. A paternoster enthusiast named David Kabele told Radio Praha that many paternosters in England and elsewhere were shut down in the second half of the 20th century because of their perceived danger, but that in Prague they remained, “because the Communist government wasn’t very afraid of European standards and norms.” It wasn’t until the 1990s, Kabele says, that some Czech buildings took their contraptions out of operation. Today, a directive in Europe forbids the construction of new paternosters.

But there are still some paternosters you can ride. One couple, who run a website called Taste of Prague and give private tours, posted a nifty map of some of their favorite paternosters in 2013. While the elevator in the Law Faculty building has since stopped operating, and another in the YMCA building has been renovated as part of European homogenization, the couple tell Smithsonian.com there is still a cluster of rideable paternosters on the list. Favorites that are publicly accessible include one at the “old-school office building” U Novaku, another at the financial directorate (Prague’s main tax office), one at the city council building and another at the Prague 7 council building. “These are the coolest ones,” Taste of Prague says.

There are also a lot of paternosters still in Germany, though many are not open to the public. In fact, just a few days ago, a blogger posted a half-joking, half-real cri de coeur about stopping EU bureaucrats from potentially banning them.

The elevator’s name, by the way, comes from the Latin for “our father,” the first two words of the Lord’s Prayer, and refers to the way the chain of cabinets moves like a rosary in a religious person’s hand. Carr, the elevator museum owner, jokes about the harrowing experience: “I know why they were called paternosters!”