Castles In medieval times, castles served as the home and fortress of a monarch or noble. The earliest castles were built from earth and wood. By the 12th century, most castles were built from stone. The stones came from local mines or quarries if possible, but sometimes they had to be carried long distances by water or on ox wagons. The roofs of castles were covered with slates, clay tiles, or wooden shingles. Castles were built on steep hill sides or at the top of rocky cliffs. This was for protection from attackers. It made it harder for them to reach the castle. Castles also had additional purposes. They sometimes served as barracks, prisons, storehouses, ar