Great Buddha Temple, Zhangye, China

Zhangye is a city that sits in the centre of the Hexi Corridor and was an important outpost on the Silk Road. It was also a border town, protecting inner China from the nomads in the northwest. Across centuries, dynasties and nomadic tribes engaged in warfare in the area, such as the Han against the Xiongnu, Western Xia conquering the Uyghur Kingdom or the Mongols exterminating Western Xia. 

In the city centre is the Great Buddha Temple. It was built in the 12th century during the Western Xia era when they controlled the Hexi Corridor and it is largely known for its massive reclining Buddha, stretching 115ft (35m) in length. It was rumoured that Kublai Khan, Mongol emperor of the Yuan Dynasty, was born in the temple and that the last emperor of the Song Dynasty was exiled here and became a monk. However, no evidence to corroborate either story has been found. 

Southeast of the city centre is Shandan County, home to several remains of the Great Wall. Although many sections have crumbled, were mowed down, got hollowed out or even had a highway cut through, the Shandan Wall is still a fine example of rammed earth construction. Two walls, from two dynasties exist beside each other, at distances between 33-262ft (10-80m). They are both built from rammed earth at least 1,500 years apart. 

The earliest, from the Han era, was built in 111 BC. Most of it has eroded or been looted, with only round mounds that were once watchtowers remaining. They are dotted alongside the sturdier and better-preserved Ming wall. A study of the two walls reveal the evolution of construction methods and the advancement of techniques and materials. 

Being located on the edge of the Gobi Desert, both walls are at risk of ongoing damage or erosion, either from ongoing human interference or the harsh desert climate.