We've been scouring the internet for Christmas traditions to do with buildings and found this one! In Finland, the majority of homes have their own sauna built in. On Christmas Eve, the sauna is designated a sacred space associated with dead ancestors. This has been a Finnish custom for many centuries. Tradition states that Finns must strip naked and take a long, respectful stint in the sauna. This is called Joulusauna in Finnish. After this they must head out to evening celebrations so that the spirits of their ancestors can take their place in the sauna!