Building the Great Wall must have been thirsty work. It was lucky for the builders all those years ago that they could buy ice water from people along the way. If it got cold, they could always buy an “I climbed the Great Wall” T-shirt and perhaps even go to KFC for dinner.

Ok, maybe this isn’t quite true. But it does make a very important point: some parts of the Great Wall have been reduced to marketplaces. Sections of the Wall close to Beijing are now full of tourists, with salespeople standing around the gate. As a result, you lose all sense of history. How can you admire the wonderful views when someone is whispering in your ear: “Sir, I give you good price.”