During the postwar era of urban renewal, Sullivan's works fell into disfavor, and many were demolished. In the 1970s growing public concern for these buildings finally resulted in many being saved. The most vocal voice was Richard Nickel, who organized protests against the demolition of architecturally significant buildings. Nickel and others sometimes rescued decorative elements from condemned buildings, sneaking in during demolition. Nickel died inside Sullivan's Stock Exchange building while trying to retrieve some elements, when a floor above him collapsed. Nickel had compiled extensive research on Adler and Sullivan and their many architectural commissions, which he intended to publish in book form.