Coffee-house legend alert: Trotsky came here to play chess, and turn-of-the-century literary greats like Karl Kraus and Hermann Bahr regularly met here for coffee. Its marble pillars, arched ceilings and chandeliers now mostly play host to tourists, and the queues can be tedious, but once in it's a deliciously storied setting for a melange and slices of chocolate-truffle Altenbergtorte.