Kingston is a city in Ontario, Canada, on the northeastern end of Lake Ontario. It is at the beginning of the St. Lawrence River and at the mouth of the Cataraqui River, the south end of the Rideau Canal. Kingston is midway between Toronto, Ontario, and Montreal, Quebec, and is also near the Thousand Islands, a tourist region to the east, and the Prince Edward County tourist region to the west. Kingston is nicknamed the "Limestone City" because it has many heritage buildings constructed using local limestone.