Not quite an answer to the question, but as late as 1990 my father's employer maintained a large analog computer (basically an enormous plug-board system for setting up coupled differential equations). It occupied a bay about 20 meters long, 4 meters deep and two stories tall (the extra overhead was filled with cable trays and ventilation ductwork). – dmckee --- ex-moderator kitten Jan 26 '19 at 6:55