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.