What Makes it German?

So I'm going to start by giving full credit to Cody for bringing this question up in the German Discussion section yesterday.

He asked a question which I found to be a really weighty one:

What makes Berlin: Symphony of a Great City a specifically German film?

We couldn't quite pinpoint it. People worked in factories all over the world in that age. Animals didn't fight exclusively in Berlin.

So what was it?

Someone suggested it was the nightlife, the general public attending shows, and the presence of the new woman.

But those things weren't exclusively German either...

So maybe the 'Germanness' comes from how it influenced other films down the road, right?

....I actually have no idea.