Though other kofun remain covered in earth, Japan's largest stone burial chamber is laid bare and you can walk inside. The tomb was looted centuries ago, and it's unclear whose remains are interred here, though Soga no Umako, a powerful member of the influential Soga clan, is a likely candidate (which would date the tomb to the early 7th century).
The sightseeing bus from Asuka Station stops at Ishibutai (¥270, 15 minutes).