Among its remains are 24 foundation-stone relics unearthed in different parts of the DPRK. The relics are believed to be conducive to strengthening the power of the kingdom.

24 basaltic stones in three rows, each with 8 stones, were unearthed around Kumsong-ri Tomb No.1, an earth-covered stone grave of Palhae Kingdom, in Hwadae County, North Hamgyong Province which was confirmed to have commonness with graves of Koguryo Kingdom.

Such foundation-stone relics were discovered in Hoemun-ri of Orang County, Songphyong District of Chongjin City and Tonghung-ri of Kim Chaek City in North Hamgyong Province.

The stones are 70-90 centimeters in length, width and height respectively.

From roofing tiles and household goods unearthed around foundation stones, the relics are believed to serve as relay stations.

Palhae Kingdom built a net of relay stations throughout its territory as part of the efforts to bolster its power.

The 24 foundation-stone relics are of great significance in studying the history and culture of Palhae Kingdom which had consolidated the centralized feudal ruling system on the basis of developed traffic and communication network.