Wongudan Altar was built in 1897 in Korea to serve as a site for the performance of the rite of heaven. The site of the complex sat between Namsan and Bukhansan; and was considered highly auspicious by geomancers. The altar complex was also designed to mimic natural elements such as the sun and moon. It was a three-story altar made of granite and was used for animal sacrifice. The top center of the altar held a conical yellow-roofed building. The altar was destroyed by the Japanese in 1931.