Yes, the Great Wall passes through the Beijing Municipality north of the city (Huairou, Miyun, etc). There are many ways to play it (e.g. solo, groups, public transit, rustic/restored) and there are even some kind of cool places to stay overnight up there. If you search this subforum for "great wall", you'll stumble upon a number of relevant threads (some of them are oldish, so maybe not up to date on transportation options, but the wall itself hasn't changed much).