Dongammun (동암문) is the eastern secret gate or ammum. It was often used by people and animals and to bring war munitions into the fortress.
The gate is located 140 meters (460 feet) west of Dongjangdae (Eastern Command Post).
There are five of these hidden gates at Hwaseong Fortress. They are inconspicuous and hidden out of sight from the enemy. A brick structure can be found above with a rounded parapet which was used to defend from enemy attack.
Construction was completed on March 25, 1796.