It has been considered that Yamamomo no Misasagi is the largest round barrow (tumulus, a round burial mound) (Ichiniwa Kofun, or the Ichiniwa tomb) in Japan; however, it cannot be called Emperor Heizei's mausoleum since it was learned through an archaeological excavation in 1962-1963 that the front part of the round barrow had been pulled down during the construction of Heijokyo (Heijo Palace).
楊梅陵（市庭古墳）は全国最大の円墳と考えられてきたが、1962-63年の発掘調査により前方部が平城京築造の際取り壊されていたのが判明したため、同古墳を平城天皇の墓とするのは無理がある。