The ancient tomb of the 16th Emperor Nintoku in Osaka,Japan

according to wikipedia,
Emperor Nintoku (仁徳天皇,, Nintoku-tennō?) was the 16th emperor of Japan, according to the traditional order of succession.[1] No firm dates can be assigned to this emperor's life or reign. Nintoku is considered to have ruled the country during the late-fourth century and early-fifth century, but there is a paucity of information about him. There is insufficient material available for further verification and study.

According to Nihon Shoki, he was the fourth son of Emperor Ōjin and the father of Emperors Richū, Hanzei, and Ingyō.

Nintoku's tomb

Daisen-Kofun, the tomb of Emperor Nintoku, OsakaDaisen-Kofun (the biggest tomb in Japan) in Sakai, Osaka is considered to be his tomb. The Imperial tomb of Nintoku's consort, Iwa-no hime no Mikoto, is said to be located in Saki-cho, Nara City.Both kofun-type Imperial tombs are characterized by a keyhole-shaped island located within a wide, water-filled moat. Imperial tombs and mausolea are cultural properties; but they are guarded and administered by the Imperial Household Agency (IHA), which is the government department responsible for all matters relating to the emperor and his family. According to the IHA, the tombs are more than a mere repository for historical artifacts; they are sacred religious sites. IHA construes each of the Imperial grave sites as sanctuaries for the spirits of the ancestors of the Imperial House.

http://en.wikipedia.org/wiki/Emperor_Nintoku