Vienna’s club U4 has been a fixed component of Vienna’s nightlife scene and has substantially influenced the city’s flourishing into a modern, open international city. Over three decades, the U4 has been the only club in Austria with international importance. Prince, David Bowie, Kurt Cobain with Nirvana and Grace Jones all have been guests in the U4. Today, international house stars, such as David Guetta and various hip-hop, pop and rock celebrities play concerts in the club. “Many stars come here to party incognito. Johnny Depp once spontaneously came over and sang some songs on stage,” Michael Groess, the manager, smiles.