Seoul in the past was a huge walled city. In the 5th year (1936) of King Taejo of the Joseon Kingdom (1392-1910), the kingdom moved the capital to Seoul. To prepare for war, control the in inflow of people and to prevent theft, a wall with Mt. Bukak as its main anchor was built along the lines of Mt. Nak, Mt. Nam and Mt. Inwang to surround the Gyeongbok Palace. The wall ran for 18.127 kilometers. To the south of the wall was the Sungnyemun, to the east, Heunginjimun, to the west, Doneuimun and to the North, Sukjeongmun.