Ayamezuka Kofun
Japan
The Ayamezuka Kofun is a keyhole-shaped kofun burial mound located in the Takenomachi neighborhood of Nishikan-ku, Niigata in the Hokuriku region of Japan. The tumulus was designated a National Historic Site of Japan in 1938.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).