‘It is the one great sight,’ said Theodore Roosevelt ‘that every American should see.’

The whole world too; of the five million visitors a year, a quarter come from abroad. The scene, over the edge of the history of the world, quickens the pulse, pumps the adrenalin and lubricates the palms. Forget the muse. The first reaction to the mile deep, inside out, upside down mountain is likely to be a rude expletive.

There are five ways to deal with it. You can hike it, ride a mule up and down it, fly over it or raft down the Colorado River, that silvery jade thread a mile below. Or you can just gawp. But at least stay a night, ideally at the historic El Tovar, once considered to be the most elegant hotel west of the Mississippi. As well as losing the day crowd you get to see two amazing trooping-of-the-colour parades, one called dusk and one called dawn.