Ichiniwa Tumulus is immediately adjacent to the north of the traces of Daigokuden (Council Hall in the Imperial Palace) in Heijo-kyu Palace, and it was once thought to have been one of the largest circular tomb mound whose diameter was over 100 meters.
平城宮大極殿跡のすぐ北に隣接しており、かつては直径100メートル超の最大級の円墳と思われていた。