The mechanism of Pater Noster elevators resembles a rosary, hence their name - "Our Father" - like in the popular prayer. It is a loop of open cabins in constant move and it dates back to the 19th century. Just hop in and hop off whenever you like. And if you have the courrage, ride through the last floor to do the full loop!
In the 21st century Pater Noster elevators are a true rarity. Apart from Prague, you will find them in just a few European cities. In many countries use of such elevators is forbidden due to safety concerns. But not in Prague - enjoy!
You can ride Paster Nosters for free in many places, e.g. in the YMCA Palace close to the Republic Square in Prague New Town.