The Wasserturm (water tower) is a grim heavy brick building up in Prenzlauer Berg in Berlin.
We walked up this way on our first afternoon, a day that mixed heavy clouds with bright sun: this became the routine for much of the trip. Here a storm brews and makes glowering light, but it never actually materializes.
I know very little about the building, especially given how forboding I find it. Google gives up only the information that the Wasserturm was completed in 1875 by the English Waterworks Company, on a design by Henry Gill. I am told that the basement of the Wasserturm proper, which is now a fancy set of apartments, was used for torture by the Nazis, but I don't have a clear source on this.