I live only a few miles from Arlington Memorial Bridge which links Arlington, VA with Washington, DC across the Potomac river. The middle span of the bridge used to be a drawbridge. Living here for 39 years, I never knew that there were abandoned offices and drawbridge control rooms beneath the bridge.
Four million pounds of iron housed in the two piers on either side of the draw span acted as counterweights and could lift the two leaves vertical in just a single minute. Hidden from view inside the bridge piers, the draw span control rooms only popped into public view when the mechanism broke down and caused traffic delays, which it did with some regularity.
Memorial raised its drawbridge for the final time on February 28, 1961. The Theodore Roosevelt Bridge under construction a third of a mile upstream was a solid concrete structure, which eliminated the functionality of Memorial's draw span. Finally in 1976, the leaves of the Memorial Bridge draw were sealed, and the doors to the control room locked for good.
Images: Elliot Carter