Stone Castles
During the 10th century, castles were beginning to be built out of stone. The main miltary and residential building of a castle could be a large stone tower, although stone towers were expensive to build, took along time to make, and needed skilled stoneworkers to build them, resulting in few stone towers being built until the 11th century.Stone towers were stronger than wooden walls and did not burn. Also, attackers had to find other ways to destroy the stone towers, such as digging tunnels beneath walls to make them collapse or chipping away at the stone corners with picks. Stone castles are now often known as Keeps, but were called great towers or donjons in their day. The Normans liked to build their great towers with thick stone walls and built several after their conquest of England in 1066. They also built many more in the next century.
Ringed Walls
In the mid 13th century, castles began to be built with rings of stone walls, one inside of the other. These were called concentric castles. The outer wall of a concentric castle was fairly close to and lower than the inner wall (sometimes so low that it seemed no more than a barrier against siege machines). But it also meant that archers from the inner wall could shoot over the heads of thoose on the outer wall, creating twice the fire power to fire on the enemy. Plus, if the enemy broke through the outer wall, they still would have to break through the inner wall.
Castles from Japan
In Japan, fortresses began to be built during the Yamato period (A.D. 300-710). Many times these fortress were just temporary strongholds, but more permanent foundations made of wood began to appear in the 14th century. Then in the 16th and 17th centuries (when castles were declining in Europe) castles became very popular in Japan. This was because of cannons not being used much in Japan.
There were three major types of Japanese castles: mountaintop (yamajiro), flatland-mountain (hirayamajiro), and flatland (chirajiro). Mountaintop castles were made in earlier times and were used mainly for warfare. These castles were almost impossible to attack because of their location. Flatland-mountain castles provided easier communication between castles, but were more likely to get taken over by enemy. Lastly, flat-land castles were mainly made because they were the fastest to build, but they could get taken over very easily. So many times, they were built with a moat for extra defense.
Castles from Germany
Many wealthy princes and nobles built castles in Germany to live in, under the leadership of the emperor. Later in the 13th century, central control broke down in Germany and many lesser lords built castles, many of which were their bases for their robbery. German castles were often influenced by the land. Many were built where the land gave them the advantage, often in hills or mountains or along the banks of the Rhine River. In other areas that were flat, Germans built Wassburg castles (a castle protected by a moat). "The Teutonic Order of monk-knights built brick castles like blockhouses(structures for defense) containing residential and religious areas set around a rectangular courtyard". Large castles from the 11th and 12th century were later given an extra wall with flanking towers for extra protection.
