Bukhansan is an 836.5m mountain straddling five Seoul districts (Gangbuk, Dobong, Eunpyeong, Seongbuk, Jongno) and three Gyeonggi cities (Goyang, Yangju, Uijeongbu). It used to go by 'Samgaksan' — 'three-horned mountain' — for its trio of jagged peaks, until it became Korea's 15th national park on April 2, 1983, and the name Bukhansan stuck. The park covers just 79.92 km² across Seoul and Gyeonggi, yet pulls in roughly 5 million visitors a year — enough to land it in the Guinness World Records as the most-visited national park per unit area on the planet. The secret? A subway ride puts you at a trailhead in about 30 minutes, making this a genuine mountain in the middle of a megacity.
Three peaks crown the summit. Baegundae (836.5m) is the highest, Insubong (810.5m) is a rock-climbing mecca, and Mangyeongdae (799.5m) rounds out the trio — together they're the 'three horns' that gave the mountain its old name. Insubong's sheer granite face draws climbers from Korea and abroad who rope up and go vertical, while Baegundae is the bucket-list summit every Seoul hiker eventually checks off.
For beginners, the easiest way up Baegundae is the Ui-dong route. Walk in from Bukhansan Ui Station (Ui LRT line), pass Doseonsa Temple, cross Harujae ridge and Baegunsanjang shelter, and you'll reach Baegundae Amdun (the fortress gate) with just 300m left to the top — 3.8km total, doable round-trip in 2–3 hours. ⚠️ Past Doseonsa the slope kicks up hard, and the final stretch is a rock scramble where you'll be gripping steel ropes — bring gloves if you can. The Baegun Visitor Support Center (open 9am–5pm) even rents out hiking boots, poles, crampons, and knee pads for free, so you can show up gear-free and still make it work.
Don't skip Bukhansanseong Fortress. Completed in 1711 under King Sukjong, this Joseon-era defense structure runs about 11.6km along the ridgelines, complete with a temporary royal palace for the king to flee to in a crisis — a real fortress, not just a wall. Gates like Daenammun, Daeseongmun, and Daedongmun still stand, and the whole site was designated a national historic site in 1968. The ridge-following fortress trail is gentler than the direct Baegundae push, so it's a great option if you want a history walk over a summit grind.
How you get there depends on where you're headed. For the Ui-dong/Baegundae route, walk in from Bukhansan Ui Station; for the fortress route, take Subway Line 3 to Gupabal Station and catch a bus bound for Bukhansanseong Entrance. Weekends and holidays get packed solid at the Baegundae summit, so aim for a weekday dawn start if you want empty-trail photos, and brace for serious crowds during spring azalea season and fall foliage. Century-old temples like Doseonsa and Hwagyesa sit right along the routes too, so you can pair hiking with temple-hopping in a single trip.