The first English castles began to appear about a thousand years ago. They were built for diverse purposes, but the most important was to prevent any further Viking raids, French invasions, Scottish raids and importantly, to show England its own magnificence. That's one of the main reasons why William the Conqueror ordered The Tower of London built.
Windsor Castle. King Edward III was born in the castle on 13 November 1312, and was often referred to as "Edward of Windsor". Beginning in 1350, he initiated a 24-year rebuilding program by demolishing the existing castle, with the exception of the Curfew Tower and some other minor outworks. He placed William of Wykeham in overall charge of the rebuilding and design of the new castle. Henry II's keep (the Round Tower) was replaced by the present keep, although it was not raised to its present height until the 19th century.
Raby Castle south west of Durham. In the early 11th Century, the lands were owned by the Viking King Cnut (Canute the Great) and this Norse connection is reflected in the name Raby -- from 'Ra' meaning a boundary and 'Bi', a settlement. It has been suggested that Cnut, the self-styled 'Emperor of the North', may have built on the site and certainly some of the extant architecture dates from this around this period. The present building was begun in c.1360 by John, 3rd Baron Nevill and in 1378 the Bishop of Durham duly granted a licence to crenellate. The Nevills were the most powerful family in the north at the time.
Bodiam Castle is situated beside the River Rother in East Sussex and was built in the late 14th century by a veteran of King Edward III's wars with France, originally as a coastal defence. In 1385, Sir Edward Dalyngrygge was given permission to fortify his house against invasion from France, but then decided to build a new stone castle a short distance away from the house.
The site of Bamburgh Castle has a history of occupation dating back to the 1st century BC. One of the oldest buildings remaining is a large Norman Keep, probably built by Henry II. In 1464, during the Wars of the Roses, Bamburgh became the first castle to succumb to cannon fire, suffering heavy damage. The ruins of the castle were restored and extended in the 18th and 19th centuries leaving little of the earlier fortifications.