Since Greek and Roman times, man has strived to establish some type of a fortification for protection and shelter. Over
pursuing centuries these evolved into a form of military and residential places known as castles.When William Conqueror, conquered England in 1066, his armies quickly erected wooden palisades (a fence of stakes or iron railings forming an enclosure or defence) establishing a presence in former Saxon kingdoms. Many of these fortresses were constructed on sites that had previously been fortified in pre-Roman times, then by Romans themselves and lastly by Saxons who established first kingdoms there. As times became less turbulent and settled, Normans became integrated into every day life and were eventually accepted by local populace. These wooden palisades slowly began to disappear, to be replaced with stone. Any new fortifications built from that time onward were constructed entirely from stone.
In Europe, this manifested into a design consisting of a single tower and outer buildings. In mountains there was no shortage of rocky hilltops on which to build these new bastions. In lower lying areas, however, islands and peninsulas were much sought after for their ease of defence.
In British Isles Normans began to dig ditches to create a small hill or mound when one couldn’t be found to build on. These mounds became first "motte and bailey" castles, some of which were built on top of old Iron Age hill forts.
A "motte" was conical hill of dirt that was built as main defence for "keep", which was were Lord and his family resided and sought refuge whilst trying to govern their surrounding territory. The keep was basically a tower with one room per floor and usually contained 3 to 4 floors.
Later, a walled area known as a “bailey” began to appear around keep with another at base of motte. Its function was to help protect keep's support functions which grew up around original tower: grain storage, wood and metal workshops, military barracks, wells, chapels and sometimes a garden or a great hall where formal functions and meetings were held.
Over intervening years, design and style of British castles would appear in various forms throughout castle building era.
Eventually, motte itself began to be replaced with stone and a new style of British castle began to appear. These castles were built without motte altogether. The tower keep, however, remained.
The ditch that had separated “motte” from bailey became a moat (a deep, wide defensive ditch surrounding a castle or town), either dry or stone-lined, or filled with water from a nearby river or lake. These Moats became a significant part of castles design.
