The Finnish sauna is a substantial part of Finnish culture. There are five million inhabitants and over three million saunas in Finland - an average of one per household. For Finnish people the sauna is a place to relax with friends and family, and a place for physical and mental relaxation as well. Finns think of saunas not as a luxury, but as a necessity. Before the rise of public health care and nursery facilities, almost all Finnish mothers gave birth in saunas.
The sauna in Finland is an old phenomenon and its roots are difficult to trace, but it's earliest versions are believed to be from 7000 BC. Bath houses were recorded in Europe during the same time period, but Finnish bathing habits were poorly documented until the 16th century. It was during the Reformation in Scandinavia that the popularity of saunas expanded to other countries because the European bath houses were being destroyed. Hundreds of years ago, when bathing was something to be done only rarely or never at all, Finns were cleaning themselves in saunas at least once a week.
One reason the sauna culture has always flourished in Finland has been because of the versatility of the sauna. When people were moving, the first thing they did was to build a sauna. Finns would use the sauna to live in, eat, address matters of hygiene, and, most importantly, give birth in an almost sterile environment. Unlike many other, more densely populated places in Europe, the availability of wood needed to build and warm the sauna has never been an issue. Another reason for its popularity is that in such a cold climate, the sauna allows people warmth for at least a short period of time. However, it is just as popular in the summer as in the winter.
Saunas are an integral part of the way of life in Finland. They are found on the shores of Finland's numerous lakes, in private apartments, corporate headquarters, at the Parliament House and even at the depth of 1,400 metres (4,600 ft) in Pyhäsalmi Mine. The sauna is an important part of the national identity and those who have the opportunity usually take a sauna at least once a week. The traditional sauna day is Saturday.
The sauna tradition is so strong that whenever Finns go abroad, they relish the chance to have a good sauna: even the Finnish Church in Rotherhithe, London, has its own sauna. Finnish soldiers on peacekeeping missions are famous for their saunas; even on the UNMEE mission in Eritrea, a sauna was one of the first buildings to be erected. A Second World War-era Finnish military field manual states that a break of eight hours is all that is required for a battalion to build saunas, warm them and bathe in them. Saunas, even in the military, are strictly egalitarian places: no titles or hierarchies are used in the sauna.