Seoul is full of spas. The Korean style bath houses 'jjimjil-bang' are everywhere in Seoul. They are a combination of spa and sauna in one and Seoulites can easily spend an entire day there. The Western style spas are typically located insid hotels.
Call it what you want; urban retreat, luxurious escape etc. One thing is for sure, going to a spa feels amazing and few people would say no the opportunity of spending an afternoon at a spas or wellness center. Relax, rejuvenate, exercise, get pampered and return back to your shopping, sightseeing and appointments energized, transformed and feeling, perhaps even looking, 10 years younger.