HOW HAVE CASTLES CHANGED OVER TIME AND WHY WERE THE CHANGES MADE?

Castles have changed over time with the use of different materials and designs.
In the the 11 century Castles were made of wood. They could be built quickly but were not very strong and caught on fire easily. From 1100 onwards Castles were made of stone. This was important as methods of attacking were getting better and Castles needed to be stronger and longer lasting. Designs changed also with rectangular towers being replaced with round towers because it was harder to climb up them.