China was home to one of the earliest civilizations in human history. Early Chinese are credited with many revolutionary inventions including paper and gunpowder, and they laid the foundations of the longest man-made structure ever built. In total, the Great Wall of China is 21,000 km long and passes through more than 400 towns across northern and central China.
However, contrary to the common view, it is not a single
continuous structure. In fact, it is a series of fortifications and bulwarks
whose origin can be traced back to the time between the 8th and 5th centuries
BC.
At the time China was divided into several smaller states
that were always conflicting with each other to expand their territory. With
frequent external threats, rulers of these smaller states started to build high
walls to keep out the intruders.
By the 3rd century BC, the warring states unified under the
Qin dynasty and their emperor set about extending the wall, while also
connecting some of the existing sections. However, the most famous parts of the
wall were built much later during the Ming dynasty, which came to power in the
14th century, about 1,700 years later.
Just one third of the wall in some of its strongest sections
were built during that era to protect against the Mongol tribes. The materials
used in the Great Wall's construction differ greatly depending on the kind of
terrain the wall passed through and the materials available in the surrounding
areas.
In many places rammed soil and wood were used while the
strongest sections of the wall were built using marble, bricks, and a secret
ingredient that has preserved it for so many centuries. The secret ingredient
is a rather unusual mortar that contains sticky rice. Introduced during the
Ming era, it proved to be as strong and waterproof as cement, and sealed the
bricks so tightly that weeds were unable to grow between them.
Much of the Ming era sections are still standing strong to
this day, even surviving drastic. Weather events and earthquakes, but building
the longest man-made structure was no easy task. Often, huge stones and massive
bricks had to be transported to mountain tops and through difficult terrains.
Without powerful machinery, laborers could only use their
bare hands and often traveled several kilometers resulting in demise from
hunger and exhaustion. That's why many laborers lost their lives during the
construction of the wall.
Today, only rough estimates can be made and some articles
put the number at around 400,000 demises. The Great Wall of China is a
testament to the skill and hard work of the millions of laborers and many parts
of the wall stood the test of time and continue to attract over 10 million
visitors every year. However, this might also become a problem in the future.
While innovative mortar solutions and stone blocks have
helped preserve the wall, not all of its sections are as well maintained. Over
the years, adverse weather conditions made around one-third of the wall
disappear. Human activity including villagers stealing building materials and
excess of tourists has also contributed to the wall's decay. Despite some of
its sections disappearing, the wall's sheer size has given rise to many popular
myths including the one that it is visible from the moon.
However, this myth is incorrect. The claim about its
visibility from the moon was first made in the 1930s and no one had traveled to
the moon or even to space at that time. The first person to set foot on the
moon, Neil Armstrong was also asked about the Great Wall's visibility many
times, but while he could see continents, lakes, and bodies of water, no
man-made structure was visible from the moon.
For the use of bricks, the Great Wall was mainly built from
rammed earth, stones, and wood. During the Ming, however, bricks were heavily
used in many areas of the wall, as were materials such as tiles, lime, and
stone. The size and weight of the bricks made them easier to work with than
earth and stone, so construction quickened. Additionally, bricks could bear
more weight and endure better than rammed earth. Stone can hold under its own
weight better than brick, but is more difficult to use.
Consequently, stones cut into rectangular shapes were used
for the foundation, inner and outer brims, and gateways of the wall.
Battlements line the uppermost portion of the vast majority of the wall, with
defensive gaps a little over 30 centimeters tall, and about 23 centimeters
wide. From the parapets, guards could survey the surrounding land. Sticky rice
mortar, consisting of sticky rice soup mixed with slaked lime, was extensively
used to hold bricks together.
No human bones or body parts were ever incorporated into the
mortar or any part of the wall, contrary to what a legend states. Communication
between the army units along the length of the Great Wall, including the
ability to call reinforcements and warn garrisons of enemy movements, was of
high importance. Signal towers were built upon hilltops or other high points
along the wall for their visibility. Wooden gates could be used as a trap
against those going through. Barrecks, staples, and armories were built near
the wall's inner surface.
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