Stone castles were defensive and could survive attacks by fire. The thickness of the walls served as a defense against weapons. The high walls also gave their archers a big view. These are some of the military reasons castles were built from rock.
They were more permanent than wood and if built correctly, stone castles would last hundreds of years. And obviously they were so grand, that only kings could afford them.
The disadvantages to stone castles were they were incredibly expensive and time consuming to build. Many medieval castles took years to build. The manpower to build these stone high rises was astounding to say the least.
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