One of the most popular places to hang in my hood (Vienna's 5th District of Margareten) is the…read moreBlockfabrik. This is a large boulder hall with lots of places to climb from easy to hard. You can do it one time or get a membership plan if you intend to go more often. And there's a nice chill cafe for eating and drinking - even if you are not going to climb. (I do def recommend drinking after climbing rather than before.) The Blockfabrik is so popular - especially late-afternoons and evenings - that I can guarantee you there will always be a lot of people 'hanging out' with you .... hanging both literally and figuratively!!