Chicago the skyscraper era, which would then be followed by many other cities around the world. Today, Chicago's skyline is among the world's tallest and densest. Some of the United States' tallest towers are located in Chicago; Willis Tower (formerly Sears Tower) is the second tallest building in the Western Hemisphere after One World Trade Center, and Trump International Hotel and Tower is the third tallest in the country. The Loop's historic buildings include the Chicago Board of Trade Building, the Fine Arts Building, 35 East Wacker, and the Chicago Building, 860-880 Lake Shore Drive Apartments by Mies van der Rohe.
Merchandise Building forces with Sears-Roebuck & Co. of Chicago in forming a 50/50 ownership in a new company, Simpsons-Sears Limited. The new firm took control of Simpson's catalogue and mail-order business and would open new Sears-style department stores in markets not already served by Simpsons. It was seen as better suited to take on competition with the strong T. Eaton Co. catalogue business and to use Sears marketing principles to expand into smaller Canadian rural and suburban markets. The Toronto Mail Order Building complex - which eventually came to be known by the less cumbersome name of "the Mutual Street Building", continued