Fire broke out in the Hongo district in early March 1657 and, driven by dry winter winds, burned for three days through the tightly packed wooden fabric of Edo, then a city of roughly a million people. Between sixty and seventy per cent of the city was destroyed and perhaps a hundred thousand people died, many trapped against closed gates and at the Sumida river, which had almost no bridges. The main keep of Edo Castle burned and was never rebuilt. The Tokugawa shogunate's reconstruction is generally described as the first systematic exercise in urban planning in Japan.
Recovery turned fire control into urban design: streets were widened into hirokoji firebreak avenues, cleared open plots called hiyokechi were designated as buffer zones, temples, daimyo compounds and the Yoshiwara quarter were relocated to the periphery, tiled roofs and plastered fireproof storehouses were promoted, and organised fire brigades were established. The Ryogoku bridge across the Sumida followed in 1659 with firebreak plazas at each end, opening the east bank and setting the direction of Tokyo's later expansion.
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