ICSE Class 6 Answered

The Great Wall of China is the longest wall in the world. Its construction began during the reign of the first Chinese Emperor Shi Huangdi of the Qin dynasty in order to protect China from barbarian tribe attacks. The wall is almost 2400 km long and varies in height - from 4.5 m to 9 m. It more or less forms the northern boundary of China and was built across a varied terrain which included deserts, mountains and plains. It has as many as 10000 watchtowers at regular intervals. It has the distinction of being the only man-made structure visible from the Moon.