The history of Sayama Pond goes back far into history. During a survey held during upgrades in the in the 1990s, it came to light that the pond was originally built 1,400 years ago around 616 A.D. In other words, Sayama Pond is a product not of nature but of humankind, built to secure water for growing crops. Measuring 3.4 km around with an area of about 40 hectares, the pond has arrived at its current form thanks to many years’ application of human knowledge and ingenuity. Records state that the monk Gyoki carried out repairs on the pond in 731 A.D. Later, the monk Chogen carried out work on the pond during the Kamakura period (1185–1333), and around the turn of the 17th century the feudal lord Katagiri Katsumoto ordered massive upgrades. Even into the modern area, the Prefecture of Osaka carried out far-reaching works on the pond 1926–1931 and 1988–2002. On March 28, 2001, the Sayama Pond Museum was opened here as well, a place where visitors can learn about the storied history of the pond in a friendly, intimate environment.