Northwestern University Library is a prime example of Chicago Brutalist architecture. It was completed in 1970 and designed by the acclaimed architect Walter Netsch of Skidmore Owens & Merrill. The cast concrete building was cleaned in 2015 using D/2 Biological Solution.
There's no job too big for D/2. The ornamented facades of this 400,000 sq ft Chicago Landmark were cleaned from top to bottom with D/2.