Where Was This Car Elevator Located?

A car elevator in Chicago, circa 1936

The above photo of a car elevator in the Loop during in 1936 has been making the rounds, via facebook, Windy Citizen, and Tumblr sites. It first came to our attention via "Letters of Note" (You remember them? They shared the 1991 letter from Madonna in which she expressed her displeasure with Chicago men.) editor Shaun Usher, who posted this via Twitpic.

But where is the exact location of the building? We suspect that this car elevator was at 35 E. Wacker, which had a car elevator system until World War II. The parking garage at 35 E. Wacker still has remnants of the car elevator inside. Workers simply drove into the elevator car, parked in their sky-high slots, then walked along the fire escape to their offices.