CN Tower

When completed in 1976, the Toronto skyline's quirky centerpiece was the tallest freestanding structure on earth. Though this title was surrendered to the Burj Khalifa in 2010 (the CN Tower still claims the Western Hemisphere), the panoramic views from 1,815 feet continue to draw some two million visitors to the observation deck every year. On clear days, kids will love soaring above the cityscape in glass-walled elevators and squinting across Lake Ontario to glimpse the vapor rising above Niagara Falls.