Aye. Germany's a bit weird, like. Bayern Munich are obviously very good, but other than that, there's little correspondence between city size and quality of the club.
The 10 largest cities are Berlin, Hamburg, Munich, Cologne, Frankfurt, Stuttgart, Düsseldorf, Dortmund, Essen and Leipzig. Of those, only Munich and Dortmund have big clubs.
Essen is a particularly bad joke, with Rot-Weiß playing in the same division as the B teams from nearby cities (Düsseldorf, Gladbach, Dortmund).