Of strategic importance since it first straddled the Spree River in the 13th century, Berlin went on to hog centre stage in the turbulence of the modern era. Today the city, restored as the nation's capital, is the focus of a mammoth project of reunification and the barometer of Germany's moods. This is the heart of Germany, with a stoic beat that echoes through grand public buildings, glorious museums and theatres, urbane restaurants, bustling pubs and raucous nightclubs. The Wall is gone but there is still a difference between East and West Berlin.