They were built in the year 1172
Shell Keep castles were built in the year 1172! +++ Not sure where the adjective "shell" comes from, but castles with a keep - the central building in the complex, and the main accommodation - were built mainly in the few centuries of the Mediaeval period , not just in one arbitrary year.
Stone keep castles were built in 11th - 13th centuries.
In 1066 by the Normans
William The Conqueror. Aka William of Normandy.
Stone or square keep castles were first built in Medieval England by William the Conqueror. Stone keep castles were the natural extension of motte and bailey castles. Motte and bailey castles were only temporary features (though many mottes exist to this day) while stone keep castles were built to last. (this was copyed and pasted off the website below.)Go to www.historylearningsite.co.uk/stone_keep_castles.htm for more information.
1847
Stone castles were built in 1277 and usually had more that one wall, the inner wall being higher than the outer ones.
the first castles were built in aroundAD900.
There is no particular year, but most castles had fires to keep warm. For more information on life in castles read this:http://www.castles.org/Kids_Section/Castle_Story/inside.htm
In Britain, the first stone keep castle was built around 1100.
A castle which have a series of different sized walls surounding them