Wrigley Building, 510 N. Michigan Avenue, Graham, Anderson, Probst, and White, 1921, view from southeast. (Contemporary postcard, collection of Thomas Leslie)

The Wrigley Building’s most striking features, however, were the two hundred high-powered incandescent projectors mounted on adjacent buildings, throwing over twenty-five million candlepower onto its facades and making the building visible—indeed, unavoidable—from the riverfront and Michigan Avenue.

Taken from Chicago Skyscrapers, 1871-1934 (University of Illinois Press, June 2013).