Mies’s last American project, this powerful Modernist structure occupies a prominent place on the Chicago River. At 52 stories and 695 ft, it is his second tallest building (after the Toronto Dominion Center). Its black anodized aluminum exterior provides vigorous expression of the structure despite limited range of materials and color. A bust of Mies gazes approving across the lobby, whose impressive scale and attention to detail stand as a testament to his vision.