This seems weird... How do you lose a "section" of the great wall? I'm sure there is a good reason, but it really makes no sense to me...

Thats because there is no one Great Wall, but many...Different emperors build different sections, rebuild some others and abandoned those that did suit their needs.

Also, really old sections of the great wall that have been overgrown look like big rocks or ridges. It's the same way Myan temples were lost in the jungles and whole cities (like Jiaohe and Khotan in Xinjiang) disappeared into the desert. If you want to train your eye for spotting it, try practicing using sattelite photos from Google Earth. It's really really hard.

What really annoys me is that any wall they find in Northern China they call "The Great Wall." This wall probably has nothing to do with the wall tourists go to see in Beijing. Still, I guess I'll have to go on out there and check it out.

I knew there had to be a good explanation, thanks guys!