Check out this gem of an image I found in the archives! This image was taken in 1938, when Park Street was lined with Elm trees and the Union Theater was just being built. You can see the contours of the stage house going up.
Fun fact: the Wisconsin Union was the first student union in the nation to identify the need for, and include, a theater in its building. The Wisconsin Union Theater has been valued by Madison audiences and by artists alike ever since, and the revitalized and improved Wisconsin Union Theater and Fredric March Play Circle will re-open in time for the 2014 Fall semester and the 75th Anniversary of the Theater in October 2014.