By Michael Webb
No American city has a greater concentration of architectural masterpieces or a stronger urban identity than Chicago, and this guide is a match for its subject. The historical span is short; little survives from before the fire of 1871. Virtually everything was created in the past 140 years: from the first steel-framed high rises to Studio Gang's Aqua, which soars on the cover. In the late 19th century and again in the postwar years, the city nurtured the great luminaries, including Sullivan, Burnham, Wright, Mies, and many more top talents, who excelled individually even as they enhanced the urban fabric.