The Great Wall of China is another colossal undertaking, in order to reach which you take the high road to Mongolia that passes through the Pa-ta-ling Gate at the extremity of the pass of Nan-kow. This highroad, which for centuries has been daily traversed by long caravans of camels, engaged in the traffic between Mongolia, Siberia, and China, was formerly paved with blocks of granite, of which no trace is now to be seen, either on that part of the road in the little town of Nan-kow, or in the difficult mountain pass, and the traveller may therefore conclude that they have either been used in the construction of houses or washed away by some torrent. Nan-kow is a walled town, like almost all those in the neighbourhood of Peking, including the curious old suburb of Chao-yung-kwan, over one of the doors of which there is an inscription in six languages, one of which has not yet been deciphered. Everywhere on the mountain sides towers and picturesque ruins of fortifications manifest how great has ever been the fear of the Chinese of the Tatars and Mongols, for protection against whom the Great Wall was built. It is divided into two parts, the inner and the outer wall, the first of which extends for nearly 1,560 miles, from Shan-hai-kwan on the Gulf of Pe-chi-li into the Province of Kan-su on the upper Yellow River. Built two hundred years before our era, needless to say, it has been often repaired and rebuilt. Near the sea it is constructed of stone, but brick has been used on the inland portions. In thickness it varies from 16 feet to 20 feet, and is about the same in height, but to the west it is nothing like so lofty. The inner wall, which dates from the sixth century, was almost entirely reconstructed by the Mings in the sixteenth century, and is 500 miles long. This is the wall to be seen from Pa-ta-ling, passing over the hill, and then proceeding right and left to climb in zigzag fashion to the very summit of the mountains. It is constructed after the model of the walls of Peking, on a substructure of stone, with two rows of brick battlements. The top is paved, and forms a roadway 11 feet in width. Its height varies, according to the irregularity of the land, between 12 feet and 20 feet, and at about every 300 feet there are towers twice the height of the wall, also surrounded by bastions and battlements. Although less imposing than the Wall of Peking, the Great Wall of China does not deserve the flippant remarks that have been made about it. Against an enemy unprovided with artillery, and horsemen like the Mongols and Tatars, it must have presented a very serious obstruction, and if occasionally they have been able to scale it, it has generally resisted every attempt at invasion. Although it has not been used under the present Dynasty, which is of Tatar origin, it has remained, thanks to the care bestowed upon it in former times, one of the best preserved monuments in China.