Quite a few keywords to me.
I live in Berlin / Germany and I am interested in the history of the city, especially at Potsdamer Platz in the 1920s and 1930s.
At the moment I was busy with the Verkehrsturm am Potsdamer Platz / traffic signal tower and was able to straighten out some inaccurate or even wrong data due to the historic sources whichg are online available now.