| Location | Sakai, Osaka |
|---|---|
| Shape | Keyhole-shaped mound |
| Mound length | 525 m |
| Period | Early 5th century |
| World Heritage | Mozu-Furuichi Kofun Group (UNESCO) |
| IHA designation | IHA-managed (no public entry) |
At 525m, Japan's longest burial mound. The 3-tiered keyhole mound rises to 35m at the rear circle (250m diameter) and 33m at the front section (300m wide). Surrounded by triple moats, the total area including water reaches about 47 hectares — roughly 11 Koshien Stadiums. Stone-paved slopes (fukiishi) once covered the mound, lined with rows of cylindrical haniwa. By volume it may surpass even the Great Pyramid of Giza. Inscribed as a UNESCO World Heritage Site in July 2019 (Japan's 23rd WHS). Note: "Nintoku Tenno-ryo" is the IHA's official name; archaeologists use "Daisen Kofun" or "Oyama Kofun." Some rank this alongside the Great Pyramid and the First Emperor's Mausoleum as one of the world's three greatest tombs.
No interior excavation permitted (IHA). Cylindrical and figural haniwa (human figures, horses, roosters, boats), Sue ware, Haji ware, and beads have been recovered from the outer embankment and outer moat. These haniwa are exhibited at the Sakai City Museum. Joint IHA/Sakai City surveys from the 1990s onward have documented the outer embankment but interior excavation remains prohibited.
A moat-side promenade circles the outer moat in about 2.8km (40 min walk). The Sakai City Museum in adjacent Daisen Park displays haniwa and related finds. A free observation deck on the 21st floor of Sakai City Hall offers a bird's-eye view of the entire mound.