Ruins were discovered when the park was built as a part of the Ikaruga hometown re-creation project in 1991. Remains of columns for palace-class buildings, roof tiles and well marks were confirmed. Especially, the roof tiles showed the same mark of wound by the mold as those of Heijo palace in the Nara period. This suggests that the both roof tiles were produced in the same kiln using the same mold. From the fact, it is thought to be the “Akunami palace” that Empress Shotoku used as a temporary palace on the royal trip, according to the articles of “Shoku Nihongi”(the Chronicles of Japan continued). The park was built on the theme of “history”, “greenery” and “water” with sufficient attention to the preservation of the underground ruins.