Bunsanseong Fortress was constructed in the 3rd year of the reign of Goryeo's King U (1377) by Magistrate Park Wi to defend against foreign enemies, but it was destroyed during the Japanese invasion of 1592. The fortress we see today was reconstructed by Magistrate Jeong Hyeon-seok in the 8th year of the reign of Joseon's King Gojong (1871). However, it is estimated that it was first built during the days of Gaya. It is a temoe-style fortress with rocks piled up like a long band at the peak of Bunsan from which downtown Gimhae, Gimhae Plains, the Nakdonggang River and the South Sea are all in a single, panoramic view. Today, fortress walls remain stretching for some 900 meters on the slope towards the city and, inside the fortress, there are two gate sites in the south and north, an auxiliary gate on the west, a well site and several other building sites. The exact length of the remaining fortress walls is 929 meters and the average x_width is about 8 meters.

Inside the fortress lies Haeeunsa Temple, which was built to pay respects to Queen Heo of Garak who had come from the sea, according to stories. The temple also enshrines portraits of King Suro and Queen Heo that were painted during the Joseon dynasty. During the Japanese invasion of 1592, monk soldiers were stationed at this temple.

The fortress is more popularly called "Manjangdae" by Gimhae locals, and this name originated from the description, "A tall tower 10,000 (man) gil in x_height," granted by Daewongun in the Joseon dynasty for this advanced base that defeats Japanese invaders. A writing of "Manjangdae" written by Daewongun himself as well as his stamp are engraved on a rock behind a beacon that was restored in 1999.