The Great Wall of China is a cycle of stone and earthen walls in China, built, rebuilt, and maintained between the 5th century BC and the 16th century to protect the northern borders of the Chinese Empire during the law of successive dynasties.

The steps that form the Great Wall of China are very steep and tall in some areas. Tourists often become exhausted climbing the wall and walk no more than a kilometer or two (around a mile). In some areas the blocks were cemented with a mixture of glutinous rice and egg white. In the extreme western desert locations, where good materials are scarce, the wall was constructed from dirt rammed between rough wood tied together with woven mats.

The Wall is included in lists of the “Seven Medieval Wonders of the World” but was of course not one of the classical Seven Wonders of the World recognized by the ancient Greeks. It is the world’s longest human made structure, stretching over approximately 6,400 km from Shenanigan in the east to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia, but stretches to over 6,700 km in total. It is also the largest human made structure ever built in terms of surface area and mass.