All great imperial cities have their architectural icons, have their skylines and monuments that are recognized throughout their sphere of global influence. The question, of course, to ask about Manhattan is how far its skyline is a Roman skyline, how far its skyline is a latter-day London skyline, or how far its skyline is in some sense a Venetian skyline.

People, generally speaking, draw parallels between today's American empire and the British empire or the Roman empire. They rarely think of the great Venetian empire that dominated the commerce of the early modern period. The Venice of Shylock, Shakespeare's merchant of Venice, seems to me, in fact, to have more in common with the New York of today than either London or the Rome of the Caesars. Why? Because Venice was quintessentially a business center. If you like, it was a place where money talked -- as loudly as it talks in New York today. And the Doge's Palace, the square of San Marco, these things were to the people of the 16th century, all around the great Mediterranean economy, these were the twin towers of the early modern period. And New York in many ways resembles Venice at the height of its power. Whenever I fly into New York, I look down and I'm struck by the resemblance between this curious island metropolis with its waterways and its crowded commercial thoroughfares and its great startling monuments -- in a way, it's like a giant grownup version of Venice. And of course, that image carries with it the intimations of mortality that must haunt all great imperial cities.