The once-divided Berlin is rejoined at Potsdamer Platz, which now links Kreuzberg with the former East once again. Potsdamer Platz was Berlin's inner-city center and Europe's busiest plaza before World War II. Bombings and the Wall left this area a sprawling, desolate lot, where tourists in West Berlin could climb a wooden platform to peek into East Berlin's death strip. After the Wall fell, various international companies made a rush to build their German headquarters on this prime real estate. In the mid-1990s, Potsdamer Platz became Europe's largest construction site. Today's modern complexes of red sandstone, terra-cotta tiles, steel, and glass have made it a city within a city.
A few narrow streets cut between the hulking modern architecture, which includes two high-rise office towers owned by Daimler, one of which was designed by star architect Renzo Piano. The round atrium of the Sony Center comes closest to a traditional square used as a public meeting point. Farther down Potsdamer Strasse are the state museums and cultural institutes of the Kulturforum.