London is a city in and the county seat of Madison County, Ohio, United States. Located about southwest of the Ohio capital of Columbus, London was established in 1811 to serve as the county seat. The population was 9,904 at the 2010 census. It is the second largest community in the United States named London. The ZIP code is 43140.
London is served by the London Public Library. In 2005, the library loaned more than 194,000 items to its 14,000 cardholders. As of 2005, total holdings were over 48,000 volumes with over 145 periodical subscriptions.