Detroit was the Silicon Valley of the 1920s — the booming home of a glamorous new industry, a place where huge fortunes were conjured in years, sometimes months. But while the creators of the computer industry have as yet bequeathed very little to the built environment, the automobile industry piled up around it an astounding American city, in astoundingly little time. The Detroit of 1910 was a thriving Midwestern milling and shipping entrepot, a bigger Minneapolis. The Detroit of 1930 had rebuilt itself as a grand metropolis of skyscrapers, mansions, movie palaces and frame cottages spreading northward beyond the line...