The McCormick Bridge House and Chicago River Museum is a hidden Chicago gem. The entrance to the museum is at river water level, then visitors climb five floors via a spiral staircase as they stroll through history as they go up. In the lime room on the ground floor of Bridge House, visitors can see the mechanics that make bridges move and look inside the inner workings of the bridge, and if If you are lucky enough to visit on the day the bridge is raised, you will be able to see the 12,000-ton counterweights moving as the 4,200-ton sheet of the bridge is lifted to allow boats to pass under it.