Great Wall of China China

Legendary

This 21,196 km wall is one of the New 7 Wonders of the World.

Photo by Keith Roper

The Great Wall isn't one wall. It's hundreds of them, built by more than twenty different kingdoms and dynasties over roughly 2,300 years.

Some run parallel to each other. Some were built, abandoned, and then rebuilt somewhere else entirely.

Nobody actually knew the full length until recently. China spent five years surveying every remaining piece with GPS, finishing in 2012.

The answer came out at about 21,190 kilometers, or 13,160 miles. That's roughly half the distance around the equator.

The first sections went up in the 7th century BC, during a time when China was split into rival states constantly at war. Those early walls weren't built to stop outsiders. They were built to stop each other.

Then in 221 BC, a ruler named Qin Shi Huang conquered every rival state and became the first emperor of a unified China. He ordered the existing walls connected into one enormous barrier along the northern frontier.

The work was brutal. Around one million laborers were put to work, roughly one out of every twenty people in the country at the time.

Those early walls were made of rammed earth, which is soil pounded down hard between wooden frames. Very little of it survives.

The wall most people picture is much newer. The Ming dynasty rebuilt it in stone and brick between 1368 and 1644, adding watchtowers and wide walkways along the top.

One more thing worth knowing: you can't see the Great Wall from the Moon. Astronauts have confirmed it, including China's own Yang Liwei.

Visit Mutianyu near Beijing for well-restored wall with far fewer crowds than the famous Badaling section. Walk a stretch of Jinshanling if you want to see the wall crumbling and wild rather than rebuilt. Climb to a watchtower and look along the ridgeline, where the wall follows the shape of the mountains instead of cutting through them.