A wood-burning stove from Harvia, of Finland, heats the sauna. The pavilion’s rough-cut pine walls are treated with tar, a preservative that yields a time-worn aesthetic.  Photo 3 of 8 in How a 1,000-Year-Old Technique Made This Pavilion

How a 1,000-Year-Old Technique Made This Pavilion

3 of 8

A wood-burning stove from Harvia, of Finland, heats the sauna. The pavilion’s rough-cut pine walls are treated with tar, a preservative that yields a time-worn aesthetic.