In many ways, Washington is a surprisingly un-American city, full of breadth, incised by wide boulevards, punctuated with circuses and partitioned by parks. A fifth of the map is shaded green. Washington’s famous National Mall is not a shoppers’ paradise with branches of Gap or Walmart, but a swathe of grass and gravel, a déjà vu of the Tuileries Gardens in Paris rather than utterly urban USA.

Washington is also a repository for some of America’s greatest treasures. Stretching for two miles, from the arm-chaired Abe at the Lincoln Memorial to the Capitol, the Mall is lined with fourteen separate museums.