In 1590, when Tokugawa Ieyasu arrived in Edo, it was just a small village with wetlands. However, it later became one of the largest cities in the world. Ieyasu and his descendants laid the foundation for this transformation. Ieyasu started by developing the city's foundation, reclaiming land from Hibiya to Shimbashi, which supported Edo's future prosperity. To improve the transportation of goods, they extended waterways around the castle and developed Nihonbashi as a key hub. This waterway network became vital for Edo's economic development. Around the castle, they organized districts with samurai residences and merchant areas, creating an orderly urban structure. During the time of the third shogun, Iemitsu, they addressed the growing water demand by constructing the Tamagawa Aqueduct in 1653, a remarkable system for its time. After the Great Fire of Meireki in 1657, they prioritized disaster prevention by widening roads and building firebreaks. As a result of these efforts, Edo grew to over 1 million people by the 18th century, surpassing cities like Beijing, London, and Paris. The urban planning initiated by Ieyasu was continued by later shoguns, making Edo a unique planned metropolis.