The Great Wall stretches for a total of 21,196 kilometers. It takes over 30 million steps to ascend the whole length of the Great Wall. But don't worry, most visitors just spend around 3 hours hiking about 4-6 kilometers, or roughly 5,000 stairs. That's more than enough time to climb it. The original wall was built during the Ming dynasty (1368-1644) to protect against attacks from northern tribes such as the Mongols. It took hundreds of thousands of workers decades to build. The wall was recently reopened to the public after being closed for maintenance for several years. But the real challenge is finding the right path. The wall has been rebuilt and expanded many times over the centuries since it was first constructed. Some parts were made of stone, others used wood or clay. Each section was designed by different people with different ideas about how to defend against attack. At its highest point, the wall stands up to 15 meters high and is thick enough for 10 cars to pass each other on their sides without touching. It varies in width from 50 meters to three miles. The majority of the wall is made of brick or stone but there are also some sections that are made of wood or clay. The wall has been reconstructed several times over the centuries since it was first built, so it's no wonder that there are now several paths up it.