The placenta chambers of King Sejong’s 18 sons (legitimate and illegitimate) and grandson King Danjong are buried in a group on top of Taebong peak, just below Seonseoksan Mountain in Wolhang-myeon, Seongju-gun. Of the 19 chambers, 14 retain their original appearance. In the case of the five sons who opposed Sejo’s usurping the throne, however, their chambers have been destroyed; only the large rectangular base stones carved with lotus leaves remain. In the case of Sejo, after he ascended to the throne, a special memorial stone on a tortoise-shaped pedestal was placed in front of the placenta chamber. The placenta chambers were placed here sometime between 1438 (20th year of the reign of King Sejong) and 1442. At the time, the tomb of Yi Jang-gyeong, who revived the Seongju Yi clan, was located here; when the royal family declared that it would use the site, however, the tomb had to be moved. When the site was repaired in 1977, several relics were found including a buncheong bowl with stamped design and matching lid, a flat-bottomed jar, and a memorial stone. The placenta chambers of the sons of King Sejong are important in studying such structures of the early Joseon Dynasty. This site is also valuable as the only one in Korea where the placenta chambers of royal princes remain intact, also because it shows the changes in the way such structures were built during the transition from Goryeo to Joseon.