Seodaemun Prison History Hall is a museum and former prison in Seodaemun-gu, Seoul, South Korea. It was constructed beginning in 1907. The prison was opened on October 21, 1908, under the name Gyeongseong Gamok. During the early part of the Japanese colonial period it was known as Keijo Prison . Its name was changed to Seodaemun Prison in 1923, and it later had several other names.