A question I asked everyone while working on this book was “What makes a building come to be loved?” A thirteen-year-old boy in Maine had the most succinct answer. “Age,” he said. Apparently the older a building gets, the more we have respect and affection for its evident maturity, for the accumulated human investment it shows, for the attractive patina it wears—muted bricks, worn stairs, colorfully stained roof, lush vines.

