King Yeongjo locked his heir in a rice chest until he died, and the heir's son became king and moved the body into a new fortress

Crown Prince Sado was born in 1735, the son of King Yeongjo by Royal Noble Consort Yeong, and was named heir in 1736. Yeongjo rebuked him for years, and the court split between the Noron and Soron factions. In the fifth month of 1762 Na Gyeong-eon accused the prince before the king. About 20 days later, on the 13th day of the intercalary fifth month, Yeongjo had his son shut inside a wooden rice chest in front of Hwinyeong Hall at Changgyeong Palace and left there. He starved to death. A royal body could not be executed, and under collective punishment the wife and son of an executed traitor would have shared his guilt^†. The chest avoided both, and Sado's son kept his place. Yeongjo restored his son's title, gave him the name Sado, "thinking with grief", made the grandson heir of a dead uncle, Crown Prince Hyojang, and forbade honours for Sado. When the grandson became King Jeongjo in 1776, his first edict outside the funeral hall began: "Ah! I am the son of Crown Prince Sado." He moved his father's tomb to Suwon in 1789 and built Hwaseong Fortress, 5.74 km of walls, around the new town. Hwaseong is a UNESCO World Heritage site. The tomb, now Yungneung, holds Sado and his wife, Lady Hyegyeong; Sado was later raised posthumously to king and emperor^†.