From Beijing we headed north to Inner Mongolia. After about seventy miles we left the the flat North China Plains and passed through the famous Gubeikou Pass into the Jinshan (Golden Mountains). Gubeikou is also the boundary between Beijing District and Hebei Province. A few miles further on we came to the Jinshanling Great Wall.
Still more on the Great Wall: this book by Julie Lovell includes the interesting thesis that the Great Wall of China has now been replaced with the Great Firewall of China: i.e., internet censorship, a subject which, blogging as I am now in a hotel room in Beijing, I am all too aware of. Even BBC's site is blocked here, to say nothing of wikipedia.com. The internet, as an amazon.com review points out, “has replaced nomadic raiders as the most threatening of China's attackers.” She also debunks the claim that the Great Wall can be seen from the moon.