After the Berlin Wall came down in 1989, techno was the soundtrack to the reunification of a divided city. Three decades later, the German capital has changed immeasurably, but its deep ties to dance music remain. These days it's Europe's techno headquarters, with thousands of people flocking to its storied clubs every weekend. Though the city becomes more modern and cosmopolitan with each passing year, the wild spirit of the post-reunification era lives on in its extraordinary clubs.