Castles were once the sole property of kings and queens. The rooms within them were usually darker and colder than those of the peasants who lived in homes without such status.
Castles were often built as a kind of fortress, with thick stone walls and few windows facing outside to keep invaders at bay. Some even had moats or drawbridges, traps, and other defenses against invading armies.
There are so many castles in the world. Some of them have been turned into museums or hotels, while others have been abandoned and left to ruin.
Some famous castles include Windsor Castle in England, Versailles Palace in France, and Buckingham Palace in London.