Chamseongdan Altar built at Manisan Mountain is known as the altar erected by Dangun, the founder of Korea, to pay tribute to the gods in heaven. It was repaired in the 11th year of the reign of King Wonjong (1270), the 17th year of the reign of King Injo (1639), and the 26th year of the reign of King Sukjong (1700) of Joseon. It had been modified a number of times that it lost its original appearance. The double pedestal consisted of a lower part made of rounded natural stone and a ‘□’-shaped upper part. On the east side of the upper pedestal were 21 stone stairs. Memorial services are said to have been performed through the Goryeo and Joseon dynasties. Today, the memorial service is performed every year on National Foundation Day. In addition, seven celestial medians light the national athletic torch in here.