Mudeungsan's name wasn't always its current meaning. During the Baekje period, the mountain went by the old place name "Mi-dong" (未冬), a Chinese-character transliteration of the native Korean word "muldeul" or "mudol," meaning wetland. During the Unified Silla period, it was called "Mujinak" or "Muak," borrowed from "Mujinju," Gwangju's name at the time. In the Goryeo dynasty, the mountain was also called "Seoseoksan" (瑞石山, "Auspicious Stone Mountain"), and over time, as Buddhism took root in Korea, people began describing the mountain as so towering that nothing on earth could be graded ("deung") against it — hence "mu-deung," or "beyond grading," a term of reverence originally applied to describing the greatness of the Buddha. A humble old word for wetland turned, over more than a thousand years, into a name that puts a mountain on par with the Buddha.
The stone pillars crowning the summit, Seoseokdae and Ipseokdae, live up to the mountain's elevated name. Roughly 87 to 85 million years ago, during the late Cretaceous period, volcanic ash deposits (tuff) from an eruption cooled slowly; as the rock contracted while cooling, tension cracks formed the mountain's signature polygonal stone columns, known as columnar joints. Seoseokdae, less weathered, presents around 200 columns roughly 1 to 2 meters wide and 30 meters tall standing shoulder to shoulder like a folding screen. Ipseokdae, more weathered, shows clearer individual pillar shapes. These formations were never seen as mere scenery — since the Goryeo dynasty, they were regarded as auspicious stones and became objects of shamanistic worship. Recognized for their scientific and scenic value, the columns were designated Natural Monument No. 465 ("Mudeungsan Columnar Joints") in 2005, and the mountain became South Korea's 21st national park on December 27, 2012.
One detail most visitors never learn: what most hikers photograph as "the summit" is Seoseokdae, but the true peak is Cheonwangbong, at 1,187 meters. Cheonwangbong sits inside a military-protected zone housing an Air Force anti-aircraft installation, so it's closed to the public except on specific dates each year, and only to visitors who register in advance. That makes Seoseokdae, at roughly 1,100 meters, the highest point hikers can legally reach without a permit. In other words, the "summit selfie" most travelers take here is, strictly speaking, taken just short of the actual summit. You can start the climb from either of two trailheads — the Jeungsimsa area in Dong-gu or the Wonhyosa area in Buk-gu — meaning you can walk out of downtown Gwangju straight onto a mountain whose name has been rewritten across fifteen centuries.