Mausoleum of Emperor Ōjin 応神天皇陵古墳
It is not the longest in Japan, but it is the one that required the most earth to be moved.
The largest mound of the Furuichi group, in Habikino. The round part measures 250 metres in diameter by 35 in height, the trapezoidal part 300 in width by 36. It is part of the UNESCO site of the kofun (the burial mounds of the rulers) of Mozu and Furuichi, inscribed on 6 July 2019.
Osaka
Furuichi