Just a great little piece of tabletop architecture, I'd guess made as part of a pretty elaborate model train set up. I love the watertower as form, minimalist and iconic, and the soft green paint on the pitched roof combined with the white and black really does it for me.
7 1/2" t x 3 7/8" wide and deep. 1920s-40s I'd guess. Some paint as evident, all to the good I think.