Photograph of the McCormick Tribune Campus Center, Illinois Institute of Technology, showing a train moving through the Exelon tube. The concrete and stainless steel tube encloses a 530-foot stretch of the Chicago Transit Authority's elevated Green Line commuter rail ("L") tracks. Photograph made... Show morePhotograph of the McCormick Tribune Campus Center, Illinois Institute of Technology, showing a train moving through the Exelon tube. The concrete and stainless steel tube encloses a 530-foot stretch of the Chicago Transit Authority's elevated Green Line commuter rail ("L") tracks. Photograph made available via Illinois Tech's institutional repository with the permission of Richard Barnes. Show less