Castles The Middle Ages was a time of war and violence, in order to protect themselves, and those under their charge, nobles and kings would construct castles. They were more than just fortresses; they were also homes and places of commerce. Over time, however, the design of Castles changed. Castles tended to be built on hills, against cliffs, or on islands. This was so the defenders in the castle could see people approaching and mean they did not have to defend from all sides at once. However before building a castle they also had to ensure; it was close enough to the towns who paid tax to it, it could control the trade routes, there was adequate supply of fresh water and building materials and had enough people nearby in order to build it and operate it. Early Castles were called motte and bailey Castles. On top of an earth mound (or motte) a timber and earth hut would be built. Surrounding this was a courtyard (or bailey) which was enclosed in a wall. Improvement in weaponry made this form of castle inadequate and they were replaced with stone Castles. These were stronger, and still followed some of the ideas used by the motte and bailey type castle. However as time progressed their designed changed and they began to create castles with concentric walls, making it even more difficult for someone to capture the castle.