Changling, the biggest mausoleum, was built for the Yongle Emperor, Zhu Di, and took 18 years to complete. Zhu Di was the Emperor who built the Forbidden City, commissioned the Great Dictionary of Yongle (Yongle Dadian) and sent the eunuch Admiral Cheng He to South-East Asia, Ceylon, India, Africa and the Arabian Peninsula Changling is surrounded by sixteen satellite tombs for Zhu Di's concubines, and the tumulus has not yet been excavated.