The essence of Beijing has always been found in its buildings. The city has no major river, no coastline. There are some hills to the west and the north, with the Great Wall stretched across them, but there is none of the geographic razzle-dazzle that created towns like Hong Kong or San Francisco or Sydney or Istanbul. As the historian Arnold Toynbee noted when he visited in the 1930s, Beijing as a city owes little to nature and everything to art. The art of which Toynbee wrote was contained within the ancient walls of the Forbidden City, where the emperor resided at the heart of old Beijing. But the art was also the buildings themselves: beautiful, angular structures that suffused the dusty soil beneath them with an imperial significance, ...