I could feel the sun’s intensity pierce through the thick folds of the course coach window curtain, and knew that the SPF 55 I’d slathered on earlier that morning just wasn’t going to cut it.  In defeat I pulled the curtain aside to reveal the lush countryside of Beijing’s outskirts.  As the bus climbed higher and higher up Yanshan mountain, my anticipation spiked as well.  In about a half an hour I’d be walking along the Middle Kingdom’s ultimate defense structure, the G...