The first four floors of the facade along Madison and LaSalle streets are made of the original marble facade from the Otis Building, the previous building on this site. The remainder of the facade is a dark cobalt blue with details in bright green. The east wall has two additional distinguishing features, a "zipper" of bay windows that run from the 19th floor to the top, and a semicircular indentation that runs from sidewalk level to the seventh floor. Moriyama & Teshima Architects designed this building, making it the tallest building in Chicago designed by a Canadian architecture firm. Holabird & Root, whose predecessor firm had designed the Otis Building on the site in 1912, served as associate architects. The use of the lower facade of the Otis Building, an example of facadism, has received mixed reviews. Chicago Tribunearchitecture criticPaul Gapp lauded the reuse of the old facade as a brave gamble that paid off and "fits its financial canyon environs in fine fashion and friendly compatability ." Gapp particularly hailed the work of the structural engineering firm Cohen-Barreto-Marchertas in preserving the Otis Building's perimeter caissons. Gapp's successor Blair Kamin, in contrast, named it among downtown Chicago's ugliest buildings, calling it a "garish intruder" that "disrupts the stately architectural canyon of LaSalle Street with its blue and Ghostbusters-green upper stories". To Kamin, the mismatch between the old and new facades was "an object lesson in why facade-ectomies don't work."
Vicinity
10 South LaSalle is located at the southwest corner of Madison and LaSalle streets in the LaSalle Street financial district. The LaSalle Street corridor is often referred to as a "canyon" due to the high number of skyscrapers there. Within the block, 10 South LaSalle adjoins 181 West Madison to the west and the Northern Trust Company Building to the south. Across the street, it faces Two North LaSalle to the north, One North LaSalle to the northeast, and 11 South LaSalle to the east. 10 South LaSalle was built slightly earlier than its neighbor at 181 West Madison, and it was originally anticipated that both buildings might be part of a common design. As a result, the lobby at the western entrance, which faces onto a narrow pedestrian alley between the buildings, is more spacious than the lobby facing LaSalle Street. Although the building is within the West Loop–LaSalle Street Historic District, it is considered a "non-contributing" property due to its having been built so recently.
