The Gongsanseong Fortress in Gongju-si, South Korea, is a testament to the rich history of the region. Originally known as Ungjinseong, the fortress was renamed during the Goryeo Dynasty and has stood for over 1,500 years. This UNESCO World Heritage site spans an impressive 2,660 meters in length, weaving through mountain peaks and valleys to form a formidable defense structure. It served not only as a military bastion but also as a royal residence, reflecting the architectural ingenuity of the Baekje period.