Guwol-san [Nine Moons Mountain] is less than 1000 m high, but is extremely prominent in the midst of the relatively flat lands of Hwanghae Province, and its commanding position on the south bank of the Daedong River (Korea's fifth largest river, and leading up to Pyongyang City).
It is strongly associated with the myth of Korea's founding-king Dan-gun, and is considered by many the mountain at which that divine sovereign retired as a Sanshin mountain-spirit. There are a few major Buddhist temples around its slopes, but the most famous cultural asset they're is the Samseong-sa [Three Saints Shrine] complex, devoted to the three holy sages central to that story -- compare it's equivalent at Jiri-san in the South. The northern authorities have permitted several spiritual nationalistic south Korean groups to visit shrine over the past 15 years, not subject to the usual restrictions on tourism within the DPRK, and allows them to conduct veneration ceremonies. I don't know to what extent Northern citizens are also allowed to do so, but apparently at least some are.
The "Three Sages" of Korea's Foundation-myth, as enshrined in the Samseong-sa: Left is Hwan-in, Lord of Heaven, center is his son Hwan-eung, and on the right is the grandson Dan-gun, who founded the first Korean Kingdom and ruled as Shaman-king for some 1900 years before "retreating and hiding" as the San-shin of Guwol-san. See pages 132-139 in my book for info.