"God is in the details," Mies van der Rohe is supposed to have said. He did not simply mean that building details are important; he meant that they are the very soul of architecture. An easy way to appreciate this is to look at how different architects handle a very simple detail, such as a door handle, a baseboard—or a stair balustrade. The function of a balustrade is straightforward: It is both a guardrail and a climbing support. Yet the variety of designs that can perform these functions is vast. Mies' balustrade at the Arts Club of Chicago (1948-51, relocated 1997), for example, is a perfect expression of his reductive minimalism: The identical square steel bars serve as handrails, stanchions, and safety rails. The result is less about functionalism (the handrail is a bit too small to be really comfortable) than about the strict minimalism that characterizes all his work. Less is more.