Since the power and security of a lord depended upon his ability to defend himself, fief owners began to build sturdy castles. Castles were designed to withstand a siege and mount a defense. This was needed to defend against attack from other barbarian tribes as well as other knights and other fiefs.
At first, castles were wooden structures, but they were too easy to burn down or destroy. By 1100 CE, castles were made of stone. Thick walls surrounded a castle. Some walls were twenty feet thick. Inside those walls were many buildings.
At the first sign of trouble, the peasants on the manor rushed to get inside the castle walls before huge doors shut them out.
Location: Castles were usually built on top of a hill if one was handy. That way, the guards would spot attackers approaching. If there was no hill, a castle would be built at the ford of a river, or the entrance to a bay or harbor. But hill tops were best.
The Moat: A moat was built around many of the castles. This was a deep ditch surrounding the castle walls, filled with water. A bridge was built to cross the moat. The bridge was raised during an attack. The moat was loaded with traps and sharp spikes in case someone tried to swim across.
The Drawbridge: The drawbridge was a bridge built across the moat. This bridge could be raised and lowered for added protection from intruders.
The Keep: One of the largest spaces behind the thick walls was the keep. The keep was a storage area topped by a huge square tower with slotted windows for castle archers to use. The keep also stored food, wine, and grain in case of siege. Sometimes invading armies would wait outside the castle, hoping to starve people inside the walls rather than attack them. This was called a siege. The keep was also used to store food for use as needed, during the winter months.
The Barracks: Other buildings made up the barracks. The barracks were the homes of the knights and their families.
The Great Hall: The Great Hall was a passageway that connected the lord's home to the keep.
The Chapel: The chapel was built either inside the lord's home or as a separate building. The chapel was a place to hold religious services.
The Gatehouse: The gatehouse was a building used by the guards at the gates. The portcullis was the grating of the iron bars at the gateway.
Interior of the castle: The interior of the castle contained staircases, bedrooms, hallways, privies (rather like an outhouse built inside the castle), women's rooms (small areas used for chatting and embroidery), possibly a laundry, and other household rooms.