Interesting facts about the Great Wall of China

The Great Wall of China represents the series of several walls have been built since the 5th century BC.

The Great Wall of China has been rebuilt and maintained from the 5th century BC through the 16th century, the majority of today's Great Wall was built during the Ming Dynasty.

The entire Great Wall, with all of its branches, stretches for 8,851.8 km (5,500 miles) from Shanhaiguan in the east, to Lop Nur in the west.

In the beginning, the Great Wall was mainly built from rammed earth, stones, and wood, in 15th century during the Ming period bricks were used for the first time.

Some portion of the Wall, especially near tourist centers have been preserved and even extensively renovated, but in many locations the Wall is in disrepair, and the worst condition is in the Gansu province where 37 miles of the Wall will likely disappear in the next two decades.

Unlike popular belief Great wall can't actually be seen from the moon, in fact the apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles away.

Great Wall of China is barely visible from low earth orbit, and this only under perfect conditions.

In 2009, an additional 290 km (180 miles) of previously undetected portions of the wall ranging from the Hushan mountains in the northern Liaoning province, to Jiayuguan in western Gansu province, were discovered.