Is America the new world empire? Presidents from Lincoln to Bush may have denied it but, as Niall Ferguson's brilliant and provocative book shows, the US is in many ways the greatest imperial power of all time. What's more, it always has been an empire, expanding westwards throughout the nineteenth century and rising to global dominance in the twentieth. But is today's American colossus really equipped to play Atlas, bearing the weight of the world on its shoulders? The United States, Ferguson reveals, is an empire running on empty, weakened by chronic defecits of money, manpower and political will. When the New Rome falls, he warns, its collapse may come from within.