Krak de Chevaliers was one of several concentric castles that the Knights Hospitaller and the Knights Templar built in the 13th century to stop Muslim armies attacking the Crusader states. The new design was necessary for the repulsion of armies that used new designs of catapults and trebuchets. Krak de Chevaliers had space for large rooms and cisterns with stone vaults. In these rooms and cisterns, the Crusaders could keep enough food and water to eat and drink for many years. The military design meant that the castle was nearly safe from attack. The stores of supplies meant that people in the castle would be safe from a siege. The design of Krak de Chevaliers is one of the best examples of a "concentric castle", along with the castles built by Edward I of England.