A 13,000 mile dragon of earth and stone
winds its way throughthe countryside of China
with a history almost as longand serpentine as the structure.
The Great Wall began as multiple wallsof rammed earth
built by individual feudal statesduring the Chunqiu period
to protect against nomadic raidersnorth of China and each other.
When Emperor Qin Shi Huangunified the states in 221 BCE,
the Tibetan Plateau and Pacific Oceanbecame natural barriers,
but the mountains in the northremained vulnerable
to Mongol, Turkish, and Xiongnu invasions.
To defend against them,
the Emperor expanded the small wallsbuilt by his predecessors,
connecting some and fortifying others.
As the structures grewfrom Lintao in the west
to Liaodong in the east,
they collectively became knownas The Long Wall.
To accomplish this task, the Emperor enlisted soldiersand commoners,
not always voluntarily.
Of the hundreds of thousands of builders recorded
during the Qin Dynasty,
many were forcibly conscripted peasants
and others were criminalsserving out sentences.
Under the Han Dynasty,the wall grew longer still,
reaching 3700 miles,
and spanning from Dunhuangto the Bohai Sea.
Forced labor continuedunder the Han Emperor Han-Wudi,
and the walls reputation grewinto a notorious place of suffering.
Poems and legends of the timetold of laborers buried
in nearby mass graves, or even within the wall itself.
And while no human remainshave been found inside,
grave pits do indicatethat many workers died
from accidents, hunger and exhaustion.
The wall was formidablebut not invincible.
Both Genghis and his son Kublai
Khan managed to surmount the wall
during the Mongol invasionof the 13th Century.
After the Ming dynastygained control in 1368,
they began to refortifyand further consolidate the wall
using bricks and stones from local kilns.
Averaging 23 feet high and 21 feet wide,
the walls 5500 mileswere punctuated by watchtowers.
一旦发现入侵者 各个烽火台就点起火 以烟传信
When raiders were sighted, fire and smoke signals traveledbetween towers
until reinforcements arrived.
Small openings along the walllet archers fire on invaders,
while larger ones were usedto drop stones and more.
But even this new and improved wallwas not enough.
In 1644, northern Manchu clansoverthrew the Ming
to establish the Qing dynasty,
incorporating Mongolia as well, Thus,
for the second time,
China was ruled by the very people the wall had tried to keep out.
With the empire’s bordersnow extending beyond the Great Wall,
the fortifications lost their purpose.
And without regular reinforcement,the wall fell into disrepair,
rammed earth eroded, while brick and stone were plundered for building materials.
But its job wasn’t finished.
During World War II,
China used sections for defense against Japanese invasion,
and some parts are still rumored to be used for military training.
But the Wall’s main purposetoday is cultural.
As one of the largest man-madestructures on Earth,
it was granted UNESCOWorld Heritage Status in 1987.
Originally built to keeppeople out of China,
the Great Wall now welcomesmillions of visitors each year.
In fact, the influx
of tourists has caused the wall to deteriorate,
leading the Chinese governmentto launch preservation initiatives.
It’s also often acclaimed as the only man-made structure visible from space. Unfortunately,
that’s not at all true.
In low Earth orbit,all sorts of structures,
like bridges, highwaysand airports are visible,
and the Great Wallis only barely discernible.
From the moon, it doesn’t stand a chance.
But regardless, it’s the Earthwe should be studying it from
because new sectionsare still discovered every few years,
branching off from the main body and expanding this remarkable monument to human achievement.