Located in Changping County, Juyongguan Pass is the most famous pass of the Great Wall, which had great strategic significance for the security of northwest Beijing in ancient times. It has two entrances, one at the south and one at the north. The south one is called "Nan Pass" and the north one is called "Bad-aling." The whole pass is located in the 11-mile-long Guangou Valley. Once there were lush flowers and trees around the pass like lay­ers of green waves; thus, Juyongguan means "Juyong Green Layers."