Great Wall of China

A long, long, long wall.

Great Wall of China is a very long, military style wall made out of stone, dirt, bricks and many other materials, and the Chinese name for the wall is Cháng Chéng, which means ‘great wall’.
The Great Wall of China is located in northern China, and runs from east to west, along what was originally the northern border of China and was mainly built to protect the country from people invading or intruding from the north, and was also used to control who enters and exits China.
Northern walls were built around various Chinese states, some of which were built as early as 656 BC, and eventually these were joined to make the Great Wall of China.
Building, and joining the existing northern state walls to make the Great Wall of China, commenced around 220 BC and was built and rebuilt over centuries, during different periods of Chinese history.
The total length of all the sections of the Great Wall of China measures 21,196 km (13,171 miles) in length and gets up to 12 meters (39 feet) high, with the main Ming section just over 8,800 km in length.

Many parts of the Great Wall of China have disintegrated, been damaged, or been removed, and are not repairable, whilst other parts have been restored.
It is estimated that between 2 to 3 million workers died whilst building the Great Wall of China, and it is said that when a worker died, they were buried inside the wall.
The Great Wall of China was declared a UNESCO World Heritage Site in 1987.
The Great Wall of China originally had between 10,000 and 24,000 watchtowers, with 1 million guards along the Ming section of the wall.
The Great Wall of China has been said to be the only man-made structure on earth visible from space with the naked eye, however this is a myth that started back in the 1750s, and the wall is only barely visible, with the right conditions, during low orbits of the earth.