Ancient Feats of Engineering.
•1) Great Wall of China.
Parts of the Great Wall were first built by princes and overlords in the Seventh Century BC as regional border defenses when China was divided into many small states. After the unification of China in the beginning of the Qin Dynasty (221-206 BC), the China’s first emperor, Qin Shihuang (you must have heard of his Terracotta Army), linked the walls of the three states in the north (Qin, Zhao and Yan). This formed the first “Wan Li Chang Cheng” (ten thousand li Great Wall, li is a Chinese unit of length, 2 li = 1 km).
Contrary to common belief, the Great Wall of China cannot be seen from the moon without aid. This pervasive myth seems to have started in 1893 in the American-published magazine The Century and then resurfaced in 1932 when Robert Ripley of Ripley’s Believe it Or Not claimed the Great Wall could be seen from the moon-even though space flight was decades away. It is questionable whether the Great Wall can be seen from a close orbit with the unaided eye
The Great Wall of China is 25 feet high in some places and ranges from 15-30 feet wide.
The highest point of the Great Wall is in Beijing at Heita Mountain (5,033 feet/1,534 meters). The lowest point is at Laolongtou (sea level).
•2) Pyramid Of Giza
The Great Pyramid of Giza, as the name suggests, is a pyramid situated in the Giza Necropolis of Egypt. It is one of the three pyramids situated in Giza and is believed to have been built as a tomb for Fourth dynasty Egyptian pharaoh – Khufu (Cheops in Greek). It is said it took around 20 years to build the pyramid and the construction came to an end around 2560 BC. The Great Pyramid of Giza makes up the main structure of a complex setting of buildings, which also include two mortuary temples that honor Khufu. Along with that, the complex has three smaller pyramids for Khufu’s wives, an even smaller “satellite” pyramid, a raised causeway that links the two Khufu temples and small mastaba tombs surrounding the pyramid, which were built for nobles.