  Many castles were built on top of steep hills, to make it more difficult for attackers to approach. It also made it easier for guards in the towers to spot approaching armies. Most castles had other means of protection, as described below.  The Walls
The walls of castles were very thick, often made from up to 6 metres of stone. They were strong enough to provide protection from battering rams and catapults. They include a lowered walkway at the top, from which defenders could fire at the enemy. Walls which surrounded the castle completely were called curtain walls; sometimes there were two of them, one inside the other. The walls often included towers that could be used to watch for attackers, and window-like slits that archers could fire from. Sometimes the towers were open at the back, so that if attackers did manage to gain entry, they couldn't safely use the towers to fire into the castle. Towers Towers were used for observation, but also as living quarters and for storage. Sometimes they were used to keep prisoners in. Originally, towers were boxes, which were easy to build, but also easy to damage during battle. They were also easy to topple, by tunnelling underneath ('undermining'). Round towers, although harder to construct, became more common because they were harder to damage (cannon balls and other projectiles would often bounce off), they could not be as easily undermined, and they contained more storage space. The Gatehouse The gatehouse was the way in and out of the castle. It was often the most strongly defended point, because it was the place where an enemy was most likely to try to break in. Quite often it included a portcullis, which was a heavy iron gate that could be lowered, and heavy wooden doors that could be securely fastened. The gatehouse also included slits from which archers could fire, as well as murder holes, which were holes in the ceiling through which missiles could be fired, or boiling liquids poured onto attackers. The Moat The moat was a ditch around the castle that made it difficult for attackers to lean a ladder against the wall, or to tunnel up to the wall to break through. A moat all by itself, because it was very deep with steep walls, made attacking a castle difficult, but often they were also filled with water by diverting a nearby stream. The Drawbridge A castle with a moat required a bridge to the main doors. These bridges were often able to be raised or lowered from the inside by ropes or chains, and a pulley or counterweight system to make the lifting easier. Most drawbridges were made of wood. The Keep A keep was a completely self-contained building within the castle, often built right onto the wall, to which defenders could retreat as a last resort during a battle. Its basement sometimes became the castle dungeon. As with some of the towers, entry to the second floor of the keep was often by ladder, which could be lifted up to make access more difficult. Keeps began as rectangular structures, but again, as with towers, designers soon learned to make them round, to make them more difficult to damage. In later centuries, the castle keep became the private residence of the castle owner. |