"This project was a curious combination of a hotel and office block wrapped in a U-shape around a 3,982-seat auditorium for opera. Completed in December 1889, it is a 10-story-high building of granite and limestone with a 17-story tower. The noble arcaded exterior is very simple in profile, has little ornament, and owes much to the architect Henry Hobson Richardson's design for the Marshall Field Wholesale Store, then recently completed in Chicago. The interior, however, is lavishly decorated with relief ornament and colored stenciled patterns, all of which brought forth Sullivan's great talent for designing ornamentation. The interior of the auditorium (restored 1967) is particularly opulent and features gilded plasterwork and countless electric light bulbs...The astonishingly effective acoustical design of the auditorium was the work of Adler, who was also responsible for all structural and mechanical aspects of the building."
http://www.britannica.com/EBchecked/topic/572949/Louis-Sullivan
The Auditorium Building is located at 430 S. Michigan Ave. It is currently known as the Chicago University Performing Arts Building of Roosevelt University.