In the middle ages castles were built by kings also barons and other important people. Also nobleman used castles to serve as their homes and to help defend their land against enemies built them. The first castle was built in 1066 onwards by the Nobleman, when the Normans came to England after Duke of William of Normandy defeated King Harold at the battle of Hastings in 1066. When he became King of England William 1 built castles all over England. William's castles helped him to rule the country. The castles were built because the Normans were...
the guidebook because some sources were written years after the events happened and some didn't. The sources that have a more chance of being reliable are the primary sources. Primary sources are sources that are written during the time something has happened and secondary sources are sources, which are written after it has happened. The sources that are primary sources are 2,4,5 &7.

The sources that are secondary sources are 1,3,6,8,9,10,11,12 & 13. This means there are many sources in the source guidebook, which could not be true so overall the guidebook is unreliable.