JINSHANLING, China - The Mongol attackers are long gone, but the vast brick-and-stone barrier that helped China repel them and other invaders still stands - and awaits a new horde of travelers who can explore and even camp out on the centuries-old fortification.

Crumbling in some areas and neatly restored in others, the Great Wall - actually a patchwork of walls - snakes over hills and through craggy ravines covering thousands of miles of Chinese countryside, dotted by watchtowers once manned by Ming dynasty sentinels.