Medieval times were very dangerous. That's why castles were built. At first they were made of wood but they soon changed to stone after castles were attacked by people with flaming arrows. Castle walls could be very thick. Some were as much as 20 feet wide at the base! Castles were built for protection, not comfort or beauty. Windows had to be very tiny because if they weren't arrows could come through. Round towers were built on the wall so the defenders could get a 360 degree view of the surrounding area. As time went on castles became more beautiful and comfortable because of the peaceful times but they still kept some defenses. The main building inside the wall was called a donjon. Defenses outside of the wall included a drawbridge, a moat, and a portcullis (an iron grid that could be lowered over the door). So the roof wouldnt burn because of flaming arrows the defenders made the roof out of tile, slate and lead.