This was the castle where Hojo Ujiteru resided before building Hachioji Castle. In 1569, he defended it against an invasion by Takeda Shingen’s large army with a small force. He then built the more easily defensible Hachioji Castle in the mountains to prepare for an attack from the west. The remains of the castle, including the dry moat and earthen walls, are in good condition, and the history of the castle can be experienced through augmented reality (AR) with the smartphone app “ＡＲ滝山城跡” (“AR Takiyama Castle Ruins”).