Frank Lloyd Wright spent half a century rethinking what a house should hold, ranging from how a family moves from the front door to the hearth, where glass meets garden, to how a concrete slab can serve as foundation, finished floor, and furnace at once. Ten houses, built between 1910 and 1952 in seven states, show what he changed, what those changes cost the people who paid for them, and what it has taken to keep the buildings standing.