10 Sauna - 25hours Hotel Cologne The Circle
You can switch off on the 7th floor with a view of the hustle and bustle of Cologne. The spa area of the 25hours Hotel The Circle, inspired by futuristic countryside utopias, is equipped with a sauna and separate relaxation area. The outside terrace is a place to cool down in winter and somewhere to relax on loungers or swings in the warmer months.
https://www.25hours-hotels.com/en/hotels/cologne/the-circle