the great wall was renovated from time to time after the qin dynasty. a major renovation started with the founding of the ming dynasty in 1368, and took 200 years to complete. the wall we see today is almost exactly the result of this effort. with a total length of over 6,000 kilometers, it extends to the jiayu pass in gansu province in the west and to the mouth of the yalu river in liaoning province in the east. what lies north of beijing is but a small section of it.

　　a map of the great wall

　　the map shows the wall running from jiayu pass of gansu province to shanhai pass of hebei province. representative sections of the great wall built in ming times are situated near shanhai pass, gubeikou and juyong pass.

　　badaling section

　　the badaling section of the great wall snaking along the mountains northwest of beijing was built at the beginning of the ming dynasty in the 14th century. being 7.8 metres high and 5.8 metres wide at the top on the average, it has battle forts at important points, including the corners.

　　located 10 kilometers south of the badaling section of the great wall and built in an 18.5-kilometre-long valley, the pass has always been an important gateway northwest of beijing. the name is believed to have its origin in the workers and slaves conscripted to build the great wall in ancient times. cloud terrace, built in 1345, was originally the base of a pagoda over looking the main road of the town of the pass. the arched gate of the terrace and the walls inside the arch are decorated with carvings. of elephants, lions, birds, flowers and heavenly kings as well as charms in six languages-sanskrit, tibetan, phats pa (mongolian), uygur, west xia and han.

　　mutianyu section

　　the mutianyu section of the great wall, 70 kilometers northeast of beijing, is linked to the gubeikou section on the east and the badaling section on the west. it is one of the best sections of the great wall.

　　the mutianyu section of the great wall is crenelatted for watching and shooting at the invading enemy. some of the battle forts on the wall are as close as 50 metres apart.

　　jinshanling section

　　located in miyun county northeast of beijing, the jinshanling division of the great wall, like the simatai division, belongs to the gubeikou section of the colossal defence barrier.

　　the battlements in the jinshanling division of the great wall are built along the ridge of a mountain, where the soldiers can resist the invading enemy by taking advantage of the high terrain.

　　a decrepit battle fort at dusk often reminds one of the battles in ancient times. 1

　　simatai section

　　located to the east of jinshanling, the simatai division of the great wall is 3,000 metres long and has 35 battle forts. the wall rises and falls with the precipitous mountain ridge, while the battle forts are located high up the hills.

　　alarm was raised by means of smoke signals, at night by fire. smoke was produced by burning a mixture of wolf dung, sulfur and saltpeter. shots were fired at the same time. thus an alarm could be relayed over 500km within just a few hours.