The Cheonseongjinseong (Korean: 천성진성) is a historic fortress located on Gadeokdo Island, Gangseo District, Busan, South Korea.

This article does not cite any sources. (September 2016)

Gadeokdo Island area was strategically important, being located at the end of the sea route from Tsushima Islands of Japan to Busan and Jinhae, and thus had been vulnerable to Japanese marauders from ancient times. After the riots of 1510 by the Japanese residents in the three southern ports which were open for trade with Japan, plans to construct a fortress to defend the area were seriously discussed. The need for a fortress came to be felt even more acutely after the Japanese aggression of Saryangjin in 1544. A breakwater was thus constructed to shelter naval vessels and a fortress was built to accommodate naval forces. It fell to the Japanese, however, during their invasions of 1592–98 and was repaired later. The remaining wall of the fortress is 960m in circumference, 4.5m in thickness and 3.5m in height. Gates reinforced with barbicans are located at the west, south and north points. The east part of the fortress is surrounded by walls of double layers with no gate. There are redoubts at the corners of the wall and at each side of the gates to make the fortress more easily defensible. There are also traces of moats outside the wall. This fortress is valuable remains revealing much information about fortress constructions during the middle Joseon period.