More model than computer, but from 1939 to 1972 there was a water driven model of the Mississippi River basin used to solve the flood models. It covered 200 acr

More model than computer, but from 1939 to 1972 there was a water driven model of the Mississippi River basin used to solve the flood models. It covered 200 acres (a little less than 1 square kilometer) and was useful until computers replaced it. https://en.m.wikipedia.org/wiki/Mississippi_River_Basin_Model https://en.m.wikipedia.org/wiki/Mississippi_River_Basin_Mode... It is unmaintained but is now a park and can be visited.