[inigyou]

Google puts the "Warsaw-Berlin Urstromtal" (glacial valley?) right in the middle of the river near the Friedrichstraße train station.

You can be browsing the area and suddenly, yep, there's a glacial valley there in the middle of the river. According to Google.

This is a large-scale geographical feature that crosses most of Germany and Poland. But actually it's in the river next to Friedrichstraße station.