Great Wall of China

Few structures in the world are as iconic as China's Great Wall, which through the centuries has served as a passage for armies, merchants, monks, envoys, explorers and tourists. Extending some 5,500 miles long, it is not one wall, but many that were built starting in ancient times and were consolidated during the Ming dynasty (1368-1644). The Great Wall was built to keep northern raiders from swooping down into the heart of China. Jeannie Ralston wrote for The Times in 2013, "The stretch of wall between Gubeikou and Jinshanling, which we hiked on the first day, is considered a prime example of Ming dynasty construction, built from 1568 through 1583 on top of a 1,000-year-old relic of a wall from the Northern Qi dynasty (550-577). Because the Gubeikou area was a strategic passage to Beijing, the more than 40 watchtowers we passed are closely spaced, and the wall was especially strong and well reinforced, constructed of brick up its 23-foot height. "As we began our hike, I was struck b