01 / Takaoka Tumulus No. 1
The lowest course of the chamber wallis flat stones set on edge.

Takaoka Tumulus No. 1, part of the Iida Tumuli Group, is a keyhole-shaped mound 72.3 m long. Its stone chamber has flat stones set on edge along the lower wall, with a ceiling laid over them, and gate-post-like stones, said to be partly restored, stand on both sides of the entrance. The city records that this construction is peculiar to the area around Zakoji and is regarded as the earliest chamber of its kind in the region.
- Mound length 72.3 m
- Stone chamber length 5.6 m
- National Historic Site, Iida Tumuli Group, 2016
