Batavia is a city mainly in Kane County and partly in DuPage County in the U.S. state of Illinois. Located in the Chicago metropolitan area, it was founded in 1833 and is the oldest city in Kane County. Per the 2020 census, the population was 26,098. During the latter part of the 19th century, Batavia, home to six American-style windmill manufacturing companies, became known as "The Windmill City".