Himalayan salt cave Spa Kamper note : added salt blocks to my infra red sauna for similar benefits
Himalayan salt wall
Twelve at Hengshan - shanghai
The Dornbracht Bathroom: The design for the rituals and relaxation
Fujiya Ginzan Yamagata / Japan Architect Kengo Kuma / ph: Jonathan Savoie
That's quite a cool idea, to have different coloured wood on the sauna walls. But then it would need decent lighting .