1929 (Showa 4 years). Mitsui Zaibatsu's headquarters "Mitsui Main Building" was completed in Tokyo Nihonbashi.
It is a large safe in the basement (1st piece). It is 50 tons only by the weight of the door. I think that loading and construction was serious.
Buildings are still present (2nd sheet from Wikipedia). https://t.co/zubeFNZtHf