People built castles for protection and defense. Many castles are sites of legends about royalty and warriors from the past. Some castles, like Windsor Castle, are famous for their paintings and treasures on display, as well as legends of royal ghosts haunting their halls. Other notable castles mentioned include Balmoral Castle, where Prince Albert built a home for himself and Queen Victoria, and structures like the Tower of London, known for its guards in distinctive uniforms. Legendary castles like those associated with King Arthur are thought to be inhabited by ghosts like Merlin living in tunnels beneath their ruins.