One of my favorite parts of the Pittsburgh Zoo is a shadowy doorway between the bear pits, with an inscription showing the dates for their start and completion, 1936-1937, and crediting the Works Progress Administration. I’ve read that this exhibit was the first effort at the zoo to do more than cage the animals, to give the bears a larger space, something more natural. I found an old image that showed what was behind the door, and how the exhibits looked in 1941. I do wonder, though, who took the bears on the final walk-through, and if the bears demanded any changes before signing off.