Richard Nixon, visiting the Great Wall of China in 1972, said: 'I think you would have to conclude that this is a great wall.'

Ronald Reagan, visiting the Wall in 1984, said: 'What can you say except it’s awe-inspiring? It is one of the great wonders of the world.' Asked if he would like to build his own Great Wall, Reagan drew a circle in the air and said: 'Around the White House.'

Bill Clinton, visiting the Wall in 1998, said: 'So if we had a couple of hours, we could walk 10 kilometres, and we'd hit the steepest incline, and we'd all be in very good shape when we finished. Or we'd be finished. It was a good workout. It was great.'

George W. Bush, visiting the Wall in 2002, signed the guest book and said: 'Let’s go home.' He made no other comments.

Barack Obama, visiting the Wall on Wednesday, said: 'It's majestic. It’s magical. It reminds you of the sweep of history, and that our time here on Earth is not that long, so we better make the best of it.' During Obama’s visit, the Starbucks and KFC at the base of the Wall were closed.