Germany is the only Western European country with an Eastern European capital. As a result, Berlin was poorer than the rest of the country, but this is no longer the case. Since reunification, Berlin has had the fastest growing economy in Germany and is now close to Hesse in terms of GDP per capita.
Berlin is odd... for several factors. Just looking at the last 100 years, I fail to see any capital (that was not directly a war zone) be: not capital, capital, divided, part of 2 countries, an exclave...
If Berlin were removed from the map, Germany as a whole would economically (loss of people, loss of income) be on average better off.
If this is the mechanism, why is Berlin not doing better?