Shirakawa-go is a village of thatched farmhouses in a mountain valley of Gifu prefecture, in central Japan, and every roof in it is pitched at close to sixty degrees. More than ten metres of snow falls here over a winter. The steep line sheds the load before its weight can crush the thatch, and it is also what gives the village its silhouette. The houses are called gassho-zukuri, after hands pressed together in prayer. They are held together with rope and timber joints without a single nail, and all of them face the same way, so the wind passes over them and both slopes of thatch get their sun. That pitch did something else as well. It left a tall attic of three or four low floors under the ridge, and those floors were a silkworm nursery, racked with trays of worms feeding on mulberry leaf. Silk is what paid for houses this size.
From the Shiroyama hill just above Ogimachi the steep roofs sit scattered among the rice paddies, with forested mountains behind them and the valley floor at your feet. Down in the lanes clear channels of water run past the houses, with small ponds between them; in May the flooded paddies hold the roofs upside down, and in a snowfall the same street turns to umbrellas and footsteps you cannot hear. Inside a house like the Wada, now a museum, you find beams black with hearth soot and an attic that still shows its silk floors. These are lived-in homes rather than exhibits. Coaches fill the lanes around midday and are gone by evening, so an early morning here gives you a different village. On a handful of ticketed evenings in the depth of winter the snow-buried houses are lit from within, and the roofs stand glowing against a dark valley. Thatch has to be replaced every thirty or forty years, and no household does it alone: under an old mutual-aid arrangement called yui, as many as two hundred neighbours turn out and redo an entire slope in one day.