To the south, at the base of the steep South Side Slopes, was a small but crowded neighborhood of workmen and their families. To the north was a huge steel mill, a railroad roundhouse and shops, and a big brewery. In between was a railroad yard with more than twenty tracks to cross. How would the workmen get to work without getting run over by switching locomotives every day? The answer was to extend 33rd Street from the Slopes to the Flats as a pedestrian tunnel under the main line, followed by a long pedestrian bridge over the railroad yards.
The bridge and the railroad yard are gone now; the tunnel remains, but since it goes nowhere it is blocked. The tunnel entrance is still attractive in its stony simplicity.