Castle

　　There are many castles in western country. In old days, only peer and their family lived in castle. Stone castles first appeared in the 9th century. It

is made of mortar(灰泥). The mortar held the bricks together. The wall is very thick.In some places, it is about thirty feet thick.
　　 The castle can be used to defend. They are often built on high mountains surrounded by a moat(护城河). This makes the castle harder to attack(袭击). a drawbridge(吊桥) lies between the door and the river. When army comes, the bridge can be hung up. The castle also has two walls. They are called Inner wall and Outer wall. There are many holes in the wall. They are used to look down and see if the visitor is friendly or not.