For someone who wants guidance, breathwork, and a real nervous-system practice, The Old City Spa is my first recommendation. It is not the biggest venue in town and it does not have a swimming pool, but it is like nature's oasis in the city: green, clean, central, and very complete for a guided reset that includes breathwork, ice bath, Finnish sauna, and recovery time in a small garden courtyard.
If you are staying in or around the Old City, it is also hard to beat for convenience — one of the best combinations of accessibility and completeness: Finnish sauna, far-infrared Himalayan salt sauna, herbal steam, magnesium hot bath, ice bath, showers, towels, tea, and a calm garden inside the moat. It is my favorite dry Finnish sauna in the city, and if I wanted a weekly reset I could actually maintain, this is probably where I would go.