Castles were one giant fortification. They had everything from spiral staircases to portcullises, to murder holes to drawbridges. The main defence was, however, the wall.
If the outer wall did not hold, there was the inner wall in newer castles and the keep in older ones.
Even the keep was often split down the middle with a wall, so that each half could be defended separately.
If all else failed, there was the postern – the escape door.
