ANYONE INTERESTED IN power must visit Persepolis. Its ruins stand defiantly in a parched valley in southern Iran, the ultimate statement of humans’ capacity to dominate vast multitudes of their fellow humans. Amid the intricately carved stairways, walls and plinths stand the two halls from which the Achaemenid Empire radiated its power, from the Indus to the Danube. The Apadana, begun by Darius in 518 BC and finished by Xerxes, was where the King of Kings received tribute from the variety of peoples he ruled. With walls sixty metres long, its huge ceiling of Lebanese cedar was supported on seventy-two columns of carved grey marble, each nineteen metres high. Next to the Apadana is the even larger Throne Hall, its massive roof once supported by a hundred columns, each of its eight carved stone doorways depicting the King of Kings wrestling with a mythical monster. The architecture of these two halls, and the stairways leading to them, was designed to inspire awe in the subjects of the Achaemenids; any tributary hoping to see the King of Kings would be so disoriented by the time he saw the throne as to be utterly prostrate at the heart of the largest empire the world had ever seen.

The British Empire has no Persepolis; its beginning and end weren’t marked by the construction and destruction of a city. London began as an outpost of another empire, and has continued to flourish long after the fall of its own. Neither is there a founding date or a battle in which Britain decisively beat its predecessor and was universally hailed as the new world power – just as there is no decisive defeat that marks its end.