Every month, five million people move from the past to the future. Pouring into developing-world "instant cities" like Dubai and Shenzhen, these urban newcomers confront a modern world cobbled together from fragments of a West they have never seen. Do these fantastical boomtowns, where blueprints spring to life overnight on virgin land, represent the dawning of a brave new world? Or is their vaunted newness a mirage?

Daniel Brook travels to a series of major metropolitan hubs that were once themselves instant cities — St. Petersburg, Shanghai and Mumbai — to watch their "dress rehearsals for the 21st century." Understanding today's emerging global order, he argues, requires comprehending the West's profound and conflicted influence on developing-world cities over the centuries.