Update: See East Peoria here, which lies under the eastern approaches of the bridge.
Completed in 1933, the soaring Cedar Street Bridge ironically no longer carries Cedar Street across the Illinois River; it’s now called the MacArthur Highway. I find it interesting in that it is probably one of the first major bridges in the United States in the Twentieth Century with no superstructure, but rather its strength lies below the road deck
Interesting links:
http://www.johnweeks.com/river_illinois/pages/illB03.html
http://bridgehunter.com/il/peoria/cedar-street/ – 10 photos.