Yangsan Bukbu-dong Fortress

The Fortress in Bukbu-dong, Yangsan (Hanja) was a Korean fortress in what is now Yangsan, South Korea. On January 21, 1963, its former site was made a Historic Site of South Korea. It is unknown when the fortress was built. Artifacts dated to the 5th century have been identified in the area. It is recorded in the Samguk sagi that a fortress was created in this area around 687, but it is unknown if this is the fortress in question. A large number of Silla culture artifacts have been discovered in the area, suggesting that it was Silla that constructed it.

Monument data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).