The Great Wall of China runs more than 21,000 kilometers (over 13,000 miles), though not as one continuous wall but rather as fortified wall sections. Some of the sections date back more than 2,500 years, but only 8.2 percent of the existing wall is original. The Mutianyu Great Wall is one of the more accessible portions. Hike (because that is what you'll be doing, even on the wall itself) up the Great Wall, then slide down the side of the mountain on the toboggan. Alternatively, explore the Simatai Great Wall, which retains a more authentic feel—save, of course, for the fake water town at the bottom. Even more remote is the Jiankou section, which is largely unrestored, so book with an experienced group like the Beijing Hikers or Wild Great Wall.