I have traveled extensively, and in my opinion, climbing the Great Wall at the Juyongguan Pass is the single most impressive day I have had at a "tourist site" (moreso than Rome, or Mt. Fuji, or the Pyramids, or anything in the U.S.A.). The climb is arduous, not for the faint of heart or legs. However, the views are spectacular - I could not be there without reflecting on the task of building and defending the wall, not to mention trying to imagine the discouragement it must have cast into the hearts of the invading armies who faced its daunting fortification. Do not visit China without seeing the Great Wall!