In the northwest and north of Beijing, a huge jagged wall winds east and west along the rolling mountains. This is the Great Wall, which is said to be visible from the moon.

The construction of the Great Wall began in the 7th century BC. The Zhou Dynasty vassal states in northern China each built their own Great Wall for defense. After Qin unified China in 22 1 BC, it connected the Great Wall to resist the invaders from the northern Xiongnu tribes and extended it to 10000 Li or 5000 km. This is the origin of the name "1 Wan Li Great Wall".

After the Qin Dynasty, the Great Wall was restored from time to time. A major renovation began in 1368 when the Ming Dynasty was founded and took 200 years to complete. The Great Wall we see today is almost the result of such efforts. It has a total length of more than 6,000 kilometers, from Jiayuguan in Gansu Province in the west to Yalu River estuary in Liaoning Province in the east. Located in the north of Beijing is only a small part of it.