Suwon Castle is built in King Jung-jo's time, and Jeong-Yak-Yong was the main part of the construction. They gave money to working people, and people even wanted to be a construction worker. King Jung-jo built Suwon Castle because his father, Crown Prince Sado was dead in a rice storage and Jung-jo wanted a safe place for his father' tomb, and he needed a place for his mother's Hwangap festival. Jung-jo's official, Jeong-Yak-Yong built a tool to pull the rocks up easily using pulley's principles.