The ancient Rideau Canal was built between 1826 and 1832, with a total length of 202 kilometers, of which 7.8 kilometers passed through the city center of Ottawa. The Rideau Canal is an important contributor to Ottawa's selection as the capital of Canada, and is also a world-renowned UNESCO. Organization of World Heritage Sites. In summer, canoe along the canals and enjoy the beautiful city views; in winter, put on ice skates and enjoy the world's largest outdoor ice skating rink!