This map was created by Tadataka Inō (1745–1818), an amateur astronomer and surveyor who produced maps of extraordinary accuracy and had a great impact on cartography in Japan. Spanning a total of 214 sheets, Inō’s large map of Japan shows the coastal outlines of the entire archipelago along with rivers and major roads. To complete the map, Inō and his team took a total of ten surveying trips over the course of more than 16 years. They used the traverse surveying technique rather than triangulation, measuring distances with fixed points based on observation, compass directions, and astronomical observations. Inō initially funded the work himself, but the Tokugawa shogunate later provided support and in the end financed 80 percent of the project. The details in Inō’s early maps impressed the authorities, who were increasingly concerned about coastal defenses and the threat of foreign intrusion. Based on a mathematical rather than a political-historical framework, Inō’s maps stood in stark contrast to traditional state cartography. However, the shogunate largely kept the maps hidden from the Japanese public, and officials continued to use and update existing kuni ezu (provincial maps) until the collapse of the Tokugawa regime in 1868. German physician Franz von Siebold (1796–1866) managed to carry a copy of Inō’s map out of Japan and had it published in Europe, where it made an impact on foreign views of Japan. Only 60 copies of Inō’s map are known to exist in Japan. This nearly-complete set of 207 sheets was discovered at the Library of Congress in 2001.