Hwangudan, Imperial altar in Jung District, Seoul, South Korea.

Hwangudan is the surviving altar complex of the 1897 imperial shrine, now reduced to Hwangungu, a three-story octagonal pavilion on a granite base with red pillars, dark wooden framework and three grey-tiled roofs with upturned corners. It stands on a raised stone platform reached by a central stair, edged by a carved balustrade, with a small stone marker at the top of the steps.

Emperor Gojong built this altar in 1897 to mark Korea's transformation from a Chinese tributary state into an independent empire through ceremonial rituals. The structure symbolized the break from previous political dependence and the establishment of new imperial sovereignty.

The name Hwangudan derives from the Chinese character 圜, originally read "won" and changed to "hwan" after the 1953 currency reform; newspapers in the 1920s still wrote "Wongudan". The altar was used for offerings to Shangdi and the Five Directional Deities on the winter solstice and New Year's Day. Since 2008 a reenactment of the Hwangudan Great Rite, based on the Gojong Daerye Uigwe, has been held annually.

The memorial sits on the grounds of the Westin Chosun Hotel and can be reached through City Hall Station exits 6 or 7. Both subway lines 1 and 2 serve this station, offering different route options for visitors approaching the area.

The three stone drums in front of Hwangungu were set up in 1902 for Gojong's 40th year as ruler. Each drum stands for a ritual instrument used in the heaven rites, and their bodies are covered with carved dragon motifs. The drums are among the few elements of the altar complex that survived the 1913 demolition.