There are also religious buildings that take important roles in Korean society and politics. The Wongudan altar was a sacrificial place where Korean rulers held heavenly rituals since the Three Kingdoms period. Since the Joseon dynasty adopted Confucianism as its national ideology in the 14th century, the state built many Confucian shrines. The descendants of the Joseon royal family still continue to hold ceremonies to commemorate ancestors at Jongmyo. It is the oldest royal Confucian shrine preserved and the ritual ceremonies continue a tradition established in the 14th century. Sajikdan, Munmyo and Dongmyo were built during the same period. Although Buddhism was suppressed by the Joseon state, it has continued its existence. Jogyesa is the headquarters of the Jogye Order of Korean Buddhism. Hwagyesa and Bongeunsa are also major Buddhist temples in Seoul.