Made of rammed earth and rubble, these fortifications became the basis for the Great Wall, most of which would be rebuilt in stone and brick during the 15th century A.D. under the Ming dynasty.
这些由夯土和瓦砾修筑的堡垒成了长城的基础。长城中的大部分用砖石砌成，在十五世纪的时候由明朝修建。
2
Time can change everything. Former solid stone bridge now also can become former royal road smoldering rubble now also can become the road certainly some pits.
时间能改变一切。昔日坚实的石桥如今也会成为断壁残垣，昔日平坦的大道如今也会成为坑洼之路。
3
In China, the slope protection for stone filled embankment mainly adopts rubble masonry structure, which has several disadvantages in construction quality control and natural landscape harmony etc.