Ladies and Gentlemen:
　　Welcome to the Great Wall.Starting out in the east on the banks of the Yale River in Leaning Province,the Wall stretches westwards for 12,700 kilometers to Jiayuguan in the Gobi desert,thus known as the Ten Thousand Li Wall in China.The Wall climbs up and down,twists and turns along the ridges of the Yanshan and Yinshan Mountain Chains through five provinces——Liaoning,Hebei,Shanxi,Shaanxi,and Gansu and two autonomous regions——Ningxia and Inner Mongolia,binding the northern China together.
　　Historical records trace the construction of the origin of the Wall to defensive fortification back to the year 656 B.C.during the reign of King Cheng of the States of Chu.Its construction continued throughout the Warring States period in the fifth Century B.C.Walls,then,was built separately by these ducal states to ward off such harassments.Later in 221 B.C.The most extensive reinforcements and renovations were carried out in the Ming Dynasty (1368——1644) when altogether 18 lengthy stretches were reinforced with bricks and rocks.it is mostly the Ming Dynasty Wall that visitors see today.
　　The Great Wall is divided into two sections,the east and west,with Shanxi Province as the dividing line.The west part is a rammed earth construction,about 5.3 meters high on average.In the eastern part,the core of the Wall is rammed earth as well,but the outer shell is reinforced with bricks and rocks.The most imposing and best preserved sections of the Great Wall are at Badaling and Mutianyu,not far from Beijing and both are open to visitors.
　　The Wall of those sections is 7.8 meters high and 6.5 meters wide at its base,narrowing to 5.8 meters on the ramparts,wide enough for five horses to gallop abreast.Two-storied watch-towers are built at approximately 400-meters internals.The top stories of the watch-tower were designed for observing enemy movements,while the first was used for storing grain,fodder,military equipment and gunpowder as well as for quartering garrison soldiers.The highest watch-tower at Badaling standing on a hill-top,is reached only after a steep climb,like "climbing a ladder to heaven".
　　There stand 14 major passes (Guan,in Chinese) at places of strategic importance along the Great Wall,the most important being Shanghaiguan and Jiayuguan.Yet the most impressive one is Juyongguan,about 50 kilometers northwest of Beijing.
　　Known as "Tian Xia Di YI Guan" (The First Pass Under Heaven),Shanghaiguan Pass is situated between two sheer cliffs forming a neck connecting north China with the northeast.It had been,therefore,a key junction contested by all strategists and many famous battles were fought here.It was the gate of Shanghaiguan that the Ming general Wu Sangui opened to the Manchu army to suppress the peasant rebellion led by Li Zicheng and so surrendered the whole Ming empire to the Manchus,leading to the foundation of the Qing Dynasty.(1644-1911)
　　As a cultural heritage,the Wall belongs not only to China but to the world.The Venice charter says:"Historical and cultural architecture not only includes the individual architectural works,but also the urban or rural environment that witnessed certain civilizations,significant social developments or historical events." The Great Wall is the largest of such historical and cultural architecture,and that is why it continues to be so attractive to people all over the world.In 1987,the Wall was listed by UNESCO as a world cultural heritage site.