Spanning over 20,000km and connecting eras of China’s history across more than two millennia, this episode we discuss an engineering monument visible from low earth orbit, The Great Wall of China.
In the west we typically learn that the wall was built to protect northern China from Mongolian invaders but the true story is a bit more complicated. The history of the Great Wall dates all the way back to the 7th century BCE, before the unification of China. At the time the region that makes up modern day China was home to a number of civilizations who built a number of walls to protect themselves from each other, and many of these smaller walls would later be joined under the rule of China’s first emperor, Qin Shi Huang, in the 3rd century BCE.
This first iteration of the unified Great Wall was built to protect China’s capital at the time, Xi’an, as well as the silk road trade route, although most of this wall does not exist today. Nearly a century later during the Ming dynasty (the period of time made famous by the movie “Mulan”) there was a need for a much more robust wall as conflicts with Mongolia had evolved into a war between the two countries.
We typically discuss the budget of the projects on the podcast, but due to a lack of written records from the time beyond songs and poetry and due to the fact that the wall was built, re-built, and maintained over the course of many centuries it is impossible to accurately estimate the cost in a monetary sense. Some researchers estimate it may have taken roughly 90,000 man-hours to construct, although this estimate may not be too accurate given the constant repairs and fortifications made to the wall.
After Mongolia ceased to be a military threat to China many parts of the wall were taken down to be used for building materials for cities and villages, and some other parts simply eroded away. Many other sections of the wall still stand today and are maintained as tourist attractions. The Great Wall has been declared one of the 7 wonders of the modern world by UNESCO, is generally the only human made structure to be included in the topography of maps, and is often said to be visible from the moon. However, NASA has confirmed this is not the case, although it is visible from orbit.
Music by: John Julius – Bandcamp.com
Edited by: Astronomic Audio