We chose the Friedrichsbad Roman-Irish baths over the Caracalla Spa as we prefer a peaceful and…read morecooler temp adult only environment (Caracalla allows children on the first floor where the cooler temperature baths are, mainly hot 90 degree Celsius saunas on the adult only 2nd floor). Friedrichsbad is 39 euro and had no time limit (recommended 3 hours, we skipped a few of the hotter saunas and the colder pools/plunge so were done in about 2.5 hours). Swimsuits are required on Wednesdays and Saturdays. On Sunday when we went, no swimsuits are allowed. The staff checking us in was informative, explaining the gradual warm up and cool down style of Roman-Irish baths. It was a calming and relaxing experience, our favorites were the hottest pool (room 9), the next cooler small whirlpool bath (room 10), and the coolest large whirlpool bath (room 11). By the time we left at 8:30pm, staffing was slimmer so we didn't get wrapped in hot towels to end our experience, but I still went into the relaxation room and got a warm towel on my own and it was a pleasant way to end the day.