It is made out of stones and wood.
Stone, brick, tamped earth, wood, and other materials
stone and wood
As of now (2008) technology it is not practical to make materials that are sufficiently strong and light to build an Earth based space elevator. This is because the weight of conventional materials needed to construct such a structure would be far too great.
The great wall of china was built so that the people of Mongolia cannot attack china from that particular side
limestone
It is crenel stone.
Not really sure other than addition
You can construct a great sentence.
Sandstone and other rocks that were found in the region.
Mud, dirt, straw, grass, stone, branches and stones.
The Great wall didn't impact the environment much as the north area of China is mostly desert-like. The building materials used to construct it did not create much of an impact either. Keep in mind, only the kind of population such as modern day's can create a huge impact. It can be argued that the wall separated a few populations of animals, but that shouldn't matter unless you're asking about evolutionary biology.
Because the Chinese warriors were strong to protect the wall