A tumulus is a large burial mound constructed for burying emperors and war lords during the 5th to 7th century A.D. Tumuli are ubiquitous in Japan. They tend to cluster together and when you visit one you could get two or more along with it. Some are, as shown below, rebuilt and some are to let nature taking over. They were the perfect play grounds for kids. I used to play at Hotouzan Kofun, located right next to my apartment at the time, and often wondered how they brought together a large amount of earth and how they cut and placed large stone pieces with their technologies. Many large tumuli had been decorated with many Haniwa, which are unglazed pottery, with different shapes and sizes, which include human figures, animals, housewares, and houses. Very interesting!