Iwase house was built by Fuji Choemon about three hundred fifty years ago. It took eight years to complete construction. Its owners changed from the Fujiis to the Iwase at the beginning of the Meiji era, about 100 years ago. It is designated as national important cultural assets. There are about 200 Gassyo Style House remaining at Gokayama and Shirakawago, and Iwase House is the largest house. It is 26.4m wide, 12.7m deep and 14.4m high.

The left side of the house is built of large Keyaki Lumber (Zelkova Tree), and a drawing room is built in a Shoin style of architecture (Samurai Style). Part of this house is four stories, and the other part is of a five - story construction. Silkworms were raised from the 3rd floor and above. The height of the floors from the 3rd floors and above were constructed shorter so that the silk worms which were fed mulberry leaves were in easy reach.

There are two reasons for making the roof steeply sloped. One is that the attic was divided into many stories, constructed so to be used effectively in many ways. The other is that because of the heavy snowfall in the winter, it was thatched at a 60-degree angle, steep enough to allow the snow to side off from the roof.

Neither nails nor clamps were used to built the house. All the joints from the 2nd floor up were fastened with Neso wood, and straw ropes.

Official Web