Tenjin-Yama Ancient Burial Mound

Ōta Tenjinyama Kofun is a Kofun period burial mound located in the Uchigashimacho neighborhood of the city of Ōta, Gunma Prefecture in the northern Kantō region of Japan. It was designated a National Historic Site of Japan in 1941. It is the largest kofun in Gunma Prefecture and the 28th largest in the country. It is the only kofun with a length in excess of 200 meters in eastern Japan.. It is also sometimes referred to as the Dantaiyama Kofun.

Source: Wikipedia