Berlin, a city that wears its scars, has always welcomed outsiders. But it has also been a battleground invaded by the French, taken over by the Nazis, occupied by the Russians and then divided down the middle by competing ideologies in the Cold War. 

Situated in the midst of a vast, flat swampy plain, exposed to the cold winds blowing in from the Russian Urals further east, Berlin is an unlikely place to have become one of Europe's great cities.