The place you're going to at the Great Wall (BADALING)is just a reconstruction of the wall and has been compared to Disney World. It's got amusement rides and is just a purpose built wall in a small loop so was never even part of the original wall. We've spoken to two people who went to this bit of the wall and both were very disappointed. I think as the major tourist site you should go to another spot on the wall. The place we went to was called Mutanyu (about 90 mins from central Beijing) and it was absolutely fantastic. There's a 3km stretch of original wall (yes, renovated slightly) that you can walk along.