About 25 miles north of the site of the upcoming 2018 Winter Olympics is Seoraksan National Park. These mountains along Korea's East Coast are a hiker's paradise in all seasons, studded with architectural and religious highlights.
Sitting, sheltered on the valley floor, is the 108-ton bronze Buddha of Shin-heung-sa temple. Founded in the 7th century, the current complex was rebuilt in the 1600's; it's one of the oldest Zen ("Seon" in Korean) temples in the world. Today's tranquility at times seems to belie the region's tumultuous past...(Incidentally, the Buddha was cast as a symbol of hopes for reunifying the peninsula.)
The granite peaks of Ulsanbawi soar thousands of feet above the temple, popular with rock-climbers. But you'll also see groups of hardy "ajumahs" ('women of a certain age') and "ajoshis" (middle-aged men) tackling the trail--they just might pass you on the way up! If you reach the top, you're guaranteed (supposedly) longevity, along with a panoramic view of the sea...
(About a 3 or 4-hour trip via express bus from Seoul. Come mid-week for tranquility; weekends, especially during the exuberantly colorful fall, it can seem like all of Seoul has come here at the same time!)