6. Berlin (Germany)The capital city and one of the 16 states of Germany. The second most populous city proper and the seventh most populous urban area in the European Union. Berlin is home to the hippest bars in the word. Friedrichshain and Kreuzberg have plenty of party options, or if you're after an underground or warehouse party head to Mitte and Prenzlauer Berg. Berlin gives the Big Apple a run for its money when it comes to the accolade, ‘The City That Never Sleeps'. Look in the right corners and offers plenty of opportunities for round-the-clock partying.