Richmond Hill (2011 population 185,541) is a town located in Southern Ontario, Canada in the central portion of York Region, Ontario. It is part of the Greater Toronto Area, being located about halfway between Toronto and Lake Simcoe. It is bounded by Bloomington Rd. (Aurora town limit) to the north, York Regional road 7 (Vaughan city limit west of Yonge St., Markham town limit east of Yonge St.) to the south, Bathurst St. (Vaughan city limit) to the west, and Ontario Highway 404 (Markham town limit) to the east. It's southern limit is about 4 kilometres (3 miles) north of the Toronto city limit, Steeles Avenue and approximately 20 kilometres (12 miles) north of the downtown core of Toronto. The town extends 14 kilometres north-south and 7 kilometres east-west. It is the third most populous municipality in York Region and the 28th most populous municipality in Canada.
Once considered the "Rose Capital of the World", Richmond Hill has in recent years seen a huge population upsurge, being Canada's fastest-growing community in the 1990s. The town is home to the world-renowned David Dunlap Observatory telescope, at one time the second largest telescope in the world, and still the largest in Canada..
It is twinned with Lakeland, Florida.