From the Wiki:
The architects for Lake Point Tower were John Heinrich and George Schipporeit, working under the firm name of Schipporeit and Heinrich; the two were students of Ludwig Mies van der Rohe, one of the best known architects of the Bauhaus movement and International Style school, who taught at the Illinois Institute of Technology in Chicago. Lake Point Tower was completed in 1968, is approximately 645 feet (197 m) tall, and was the tallest apartment building in the world at that time. The project developer was William F. Hartnett, Jr., chairman and founder of Hartnett-Shaw Development Company, which was responsible for more than 260 residential and commercial real estate developments in the United States from 1961–1983.
Because of its height and lakeside site, the skyscraper had to be designed to withstand high winds. At the center of the building is a triangular core, 59 feet wide, that contains nine elevators and three stairwells. This core holds all of the vertical weight of the building, allowing the perimeter columns on the facade to be much smaller.
Radiating from the core are three arms that form an asymmetrical Y-shaped floor plan. The original four-armed design was changed to a three-armed design (120° apart). The outer walls are curved to prevent residents from seeing into other condominiums. The façade of the building is a curtain of bronze-tinted glass framed by gold-anodized aluminum, which reflects the sunlight off of Lake Michigan and looks golden.