Heights of mottes varied from 10 feet to 100 feet and their basal diameters from 100 to 300 feet. When workers had completed building the mound, they then covered its slopes with an outer layer of clay to prevent uneven settlement and slippage, which is probably why so many have survived.

Generally, mottes were crowned with a wooden tower, which was basically a look-out and an elevated fighting point. Often times, the tower provided accommodation for the lord of the castle. Later, some of these wooden towers were replaced by stone shell keeps.

Sometimes, motte and bailey castles evolved into very large and impressive stone fortresses, when walls, gatehouses, towers and other structures replaced the timber defenses. But, mostly what you see today is just a tree covered mound.

Baileys are associated with motte castles. They were large areas of additional space adjacent to the motte which were enclosed with a circular earthwork, a mound lower than the motte. Most of the domestic buildings for the castle would be placed in the bailey, including the stable, hall, kitchen, chapel and workshop. Even weapons were stored here for safe keeping. Some larger castles had an inner and outer bailey, and most baileys were either circular, oval or square in shape.

Motte and bailey castles could be built very quickly, some being raised in only eight days. The largest motte and bailey castle in Britain is thought to be Old Sarum, located in Wiltshire, England. The first Norman motte castle to be built in Britain was Hastings, built in 1066, at Hastings, England.

Stone Castles
Stone castles began to be built in Britain in 1067. Chepstow Castle is the oldest surviving stone castle, and may have been the first of this type to be built in Britain. Sometimes it is difficult to say just when stone castles were built, because a castle went through many building phases. Many were added to, improved and altered over a great time period up to four centuries.

Much of the time, the first stone structure was a great tower. Stone towers, or keeps, also replaced the wood towers on the mottes of the motte and bailey castle.

Stone Enclosure Castles
Many of the earliest castles were surrounded by earthworks to help in defense. But, for discussion purposes, I will talk about stone enclosures. These began to appear as early as 1088, when William Rufus (William II) authorized the building of an enclosing wall around Eynsford Castle in Kent.

Enclosure castles were also built from the ground up, not just as additions to already existing castles. Some had great towers and some did not. Richmond Castle, built in 1071, is a good example. It had a triangular enclosure, as did Caerlaverock Castle in Scotland. The enclosing curtain wall generally followed the outline of the castle, but a common enclosure for a new castle was the square enclosure.

Stone towers would also be built, or inserted, at regular intervals in the enclosing curtain wall. This was done to further enhance the defense of the castle.

Concentric Castles
The concentric castle was an enclosure castle with an additional curtain wall built, in close proximity, around the entire enclosure. In a sense, the concentric castle consisted of "walls within walls", where the inner walls, gatehouses and towers were higher than the outer walls, gatehouses and towers. This was so that soldiers fighting from the higher set of walls could shoot at the enemy and avoid hitting their fellow soldiers standing on the lower, outer set of walls.

Caerphilly Castle in Wales, begun in 1268, was the first concentric castle built from the start in the concentric style. The idea for this type of castle probably originated in the Holy Land, where great concentric castles, like Krak des Chevaliers, were built. Knights from Britain who fought in the Crusades would have seen these castles, and when they returned home, would have used the idea to build their own castles.

Some of the older castles which were originally enclosure castles or motte castles were eventually converted to concentric castles. Many of the great Edwardian castles were built from the start as concentric castles, and some scholars consider them to be the greatest of this type. One fine example is Beaumaris Castle, in Anglesey. Begun in 1295, it was never completed.

Tower Houses
Tower houses are most common to Scotland, although there are some in Northern England. In 1535 an Act of Parliament declared that land owners that had land worth over £100 were to build a tower or castle. This would enable the land owner to defend his property.

Tower houses are similar to a rectangular keep. The entrance was moved to the lowest level, and the walls of the tower house were less fortified. In the 16th century comfort became a priority and tower houses became more spacious.

Tower houses most often contained one room for each floor, and many rose four stories or more. Wings and towers were incorporated into the design, or added on at a later building period

There are two basic types of tower houses, based on the design plan, or shape. You have the L-plan and Z-plan types. The L-plan was a rectangular or square tower house with a tower or an additional wing/building on one corner. The Z-plan was a rectangular or square tower house with towers or buildings/wings at the two diagonally opposite corners.

Most tower houses did not have curtain walls and baileys, or they were removed during remodelling. Windows were small, and located above the first floor. Tower houses differ from pele towers, in that the pele towers were plain rectangular or square structures and most often had curtain walls.

Many tower houses are still lived in, and some are open to the public to be viewed.

Fortified Manors
A manor was an estate held by and the principle dwelling house for a lord. Most of the time, the lands surrounding the manor were farmed and taken care of by people who owed the lord money or service.

Manors were sometimes given a kind of defence, whether it be a ditch, moat, or palisade. This was to protect them from damage from animals or being taken by an enemy. There were very few fortified manors before the 12th century, but by the 13th and 14 centuries it was becoming common for the king to grant licences to crenellate.

Many private houses were fortified during this time frame, some to such an extent that they became known as castles. One early fortified manor house was Stokesay Castle. Fortifications were made by Lawrence de Ludlow, after receiving a licence to crenellate in 1291. A moat surrounded the castle and the enclosing walls were 30 feet high.

Another fortified manor is Weobley Castle, located on the Gower Peninsula in Wales. It was built by David de la Bere in the 14th century, and had walls 7 foot thick. There was a keep, hall, chapel, and other features that you would expect to see in a castle.

It is believed that Thornbury Castle was the last fortified manor to be built in England. Edward Stafford, Duke of Buckingham, began building it in 1511, without a licence. Stafford was executed in 1521 and the castle was never completed. It was taken over by King Henry VIII who transformed it into a palace.