A form of storehouse which provided a fireproof place to keep valuables which were otherwise always at risk in highly combustible Japanese timber houses. It had a wooden structural frame externally covered by mud daub, *tsuchikabe 土壁, about 20-30 cm thick and usually finished with a smooth coat of white or black plaster, *shikkui 漆喰. Internally the timber framework was exposed. Generally, in 17th-century urban centers, dozō had tiled roofs, but in districts where tile was difficult to obtain, the plasterwork covered the top of the structure to make it fireproof. It also had a second, independent outer structure roofed with thatch or shingles erected over it to protect the plaster from rain. Parts of walls exposed to rain were also tiled to protect plaster in certain districts. Openings were kept to a minimum, and thickly plastered swing doors and shutters with interlocking flanged reveals, *kannonbiraki tobira 観音開扉, were used both for entrances and for the few small windows. Miniature roofs, *kiriyokebisashi 霧除廂, were often provided to protect window and door surrounds from the elements. To prevent fire, the doors were closed and the joints sealed with mud that was kept in buckets nearby, rendering the dozō fireproof. Dozō became a symbol of wealth not merely because they were used to store valuables, but also because they were expensive and time consuming to construct. The low thermal conductivity of the thick walls kept the internal temperature of the dozō remarkably stable, also making it a suitable location for the manufacture of food products such as rice wine, sake 酒, and soy sauce, shōyu 醤油. It thus became an important form of proto-industrial architecture. The appearance of the word dozō in a donation letter of 1294 by the priest Shinsei 信聖, and on an illustration in the 14th roll of the early 14th century "Kasuga Avatar Miracle Scroll" (Kasuga Gongen genki-e 春日権現験記絵) confirm the existence of this building type by the end of the Kamakura period. Although dozō were used for storage purposes in the residences of the ruling classes, they are particularly associated with merchants, shōnin 商人. Dozō appear within the plots of the larger merchant establishments in the early 17th-century screens *rakuchū rakugai zu byōbu 洛中洛外図屏風, but were still a relative rarity. They spread from major urban centers to provincial towns and farming villages during the Edo period and thereafter. Most dozō were 2 story, but 3 story dozō were a status symbol among wealthy merchants from the 17th century, and an example is preserved in the old quarter of Tondabayashi 富田林, near Osaka.