No metropolitan area is complete without a multi-purpose megaplex, so you probably already know the deal. Erected by Austrian architect Roland Rainer in the mid-20th century, the Wiener Stadthalle is the city’s most important and all-encompassing arena. While the actual building itself is a bit of an eyesore—a window-paneled, flat-topped rectangle—the event center is the only space to host big-time fairs, conferences and headlining acts like the Spice Girls and U2.

Currently, Stadthalle is one of the oldest and most-used halls in Europe; their biggest hall, “Hall D”, flaunts a capacity of up to 17,000 people.