This old brewery got turned into a spa. The rooftop pool has amazing views over the city. Inside there's plenty of saunas and steam rooms. Gets super busy on rainy weekends. I'd go for the Roman-Irish spa thing for CHF 60 - you get the rooftop pool plus an entire ritual with different saunas, steam rooms, cold bath, scrubbing etc.. Basic entry with rooftop is CHF 36.