By research by excavation, a stone wall was found below the earthwork of Arioka-jo Castle and, as there were diverted stones such as tombstones, it attracted attention as possible forerunner of stonewall.
発掘調査から有岡城の土塁の下から石垣積みが発見され、墓石などの転用石材があり石垣の先駆ではないかと注目されている。