From the World Heritage inscription:
The Rideau Canal, a monumental early 19th-century construction covering 202 km of the Rideau and Cataraqui rivers from Ottawa south to Kingston Harbour on Lake Ontario, was built primarily for strategic military purposes at a time when Great Britain and the United States vied for control of the region. The site, one of the first canals to be designed specifically for steam-powered vessels, also features an ensemble of fortifications. It is the best-preserved example of a slackwater canal in North America, demonstrating the use of this European technology on a large scale. It is the only canal dating from the great North American canal-building era of the early 19th century to remain operational along its original line with most of its structures intact.
The Rideau Canal is actually an enormous structure which goes from the Rideau River to Lake Ontario, however, the most famous part lies just below Parliament Hill in Ottawa. It is easy to see and explore if you are visiting Ottawa, but it can also be seen in many other places in Ontario as well. In the winter the frozen canal is plowed to create the world’s largest ice rink.
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