This four-level house sits atop a steep, wooded hill. Arata Endo, Wright’s trusted collaborator in Japan, added to Wright’s plans three tatami-mat rooms with shoji sliding panels and, on the salon’s clerestory level, tiny doors inspired by the transoms of traditional Japanese houses to allow cross breezes. The stonework on the interior and exterior is Oya-ishi, a Japanese rock created from lava and ash and also used extensively on the Imperial Hotel. In 1947, the house was purchased by Yodogawa Steel Works. In 1974, it was designated as an Important Cultural Property, the Japanese equivalent of a national landmark. Restoration work was completed in the mid-1980s and the house was first opened to the public as Yodoko Guest House in 1989.