Although Kyokan traces of local powerful families ranging from the tumulus period to the Nara period have been discovered many, is famous Mitsudera ruins among others, Gunma Prefecture. Kyokan exhibits a square of the outer diameter of about 160m, interior surrounded by a moat is no one side 86m square square cone shape. Moat is obtained by changing structure and river channel of the river. Slope of the moat is Yes laid a few facing stones, fence of three rows had been provided on the cliff edge of the table-like portion. There are some places in the overhanging portion of the base-like portion, here and outside is believed to have been connected by a wooden bridge.
Kyokan inside had been separated into two regions in the fence row. One side, there are a number of drilling Tatsuhashira type building and the well, had been on the other side of a plurality of pit dwelling built. Horitsu pillar-type building is the main hall of the center, the opening 14m, a depth 13.6m, has been estimated that there has been an eaves part in the eaves. Tatsuhashira type building drilling of about three hotels have been arranged is behind this building.
Kyokan of powerful families of the tumulus period, enclose a fairly wide moat was a square with the keynote as Mitsudera remains, in many cases have built anything hotels a large building on the inside. Its scale is from what one side of the small size of about 90m to a large size that exceeds the 200m in outer diameter. Inside and outside of the moat is surrounded by embankments, it was allowed to coalition the fence and HoTatsuhashira. Kyokan part is also Tatsuhashira type building drilling, but the principal seems to have been as usual pit dwelling. In Uenomiya ruins of Sakurai, of the Asuka period tetrahedral Hisashiho Tatsuhashira building has been detected.