Most of the Kofun have a keyhole-shaped mound in Japan. The front of the mound of Nintoku-ryo consists of three layers, with a total length of about 486 meters , and the round rear part has a diameter of about 249 meters and a height of about 35 meters. The entire mound is surrounded by three moats. Nintoku-ryo is believed to date from the middle of the fifth century. Emperor Nintoku was the 16th emperor of Japan. He is considered to have reigned from 313- 399.