I recently visited a similar thing called "miniature world" in Victoria B.C. built by the same kind of fanatics for detail, though not nearly on the scale of the Hamburg one. The theme, broadly, is the unification of Canada by railroads in the 19th and early 20th centuries. Astonishing detail and imagination. Definitely worth a visit (on the rear side of the Empress Hotel in the center of the city), and they speak quite proper English, eh.