Tsukuriyama Kofun is one of Japan's largest keyhole-shaped burial mounds, built in the first half of the fifth century on the Kibiji plain. Its scale is hard to grasp from ground level until you walk the edges and realise the mound is more landscape than monument.
The site fits naturally with a Kibiji cycling or train-and-walk day from central Okayama. It is quiet, open, and best for travelers interested in Japan before temples and castles became the dominant visual language.