From the ground, large kofun often look like just another hill or mountain. But from the air their particular keyhole shape can be seen. A keyhole-shaped kofun is typically a tumulus divided in a part where a royal was buried (the round part of the ‘keyhole’) and a space for the performance of rituals. Nowadays, kofun are the property of the Japanese emperor. They are forbidden territory. Japanese people still believe that they hav mysterious powers and incorporate them in their religious beliefs.
Kofun are thought to have been built between the third and seventh century AD. The stories of their construction are similar to those of the Egyptian pyramids and other ancient megastructures: it took thousands of workers several years to build them.
But what if the construction itself is much older? It just seems too large and to exact to have been built by a large workforce in those days. Who made the exact keyhole shape, that can only be recognized from the air, and why? What if the structures were already there and was re-used as a burial ground for the emperor? Why are they called ‘ancient’? Did 3rd century Japanese culture still have knowledge that is lost today?