Gwanmoon-sung fortress is the best-kept fortress among all the historic fortresses in and around Gyeongju. The walls, gate, storehouse site are as they were.
This fortress was built in 722, the 21st year of King Sungduck, to protect the Silla capital of Gyeongju from enemies coming from the southeast, formerly called Mobulgoon-sung or Mobulgwanmun, it was renamed Gwanmoon-sung during the Josun period(1392~1910).
This fortress is composed of 40~50cm, long stones, piled in the running bond method of wall construction: wider at the base and narrowing gradually to reach a height of 4~5m.
The wall starts at the southern end of the Chisooll-young(mountain) range about 765m above sea level and follows the border between the provinces of Gyeongsangbook-do and Ulsan Metropolitan City, till it reaches the eastern end at Mohwari.
The total length is about 12km, which is why the local people call it 'Malli-sung', meaning 10,000 li - long wall. (Li is a traditional unit of measure.)