The CN tower, Toronto's main landmark, reaches 553.3m into the sky  and was the world’s tallest free-standing structure in 1975. The CN Tower (named after the Canadian National Railway) was initially conceived to be a TV and radio communications tower to serve the city of Toronto.  It can be seen from as far as Aurora, ON (approx. 40km away), Hamilton, ON (approx. 60km away), and even Fort Niagara State Park in New York State, USA. 

 

In 2011 the CN tower opened the EdgeWalk which allows visitors to walk around the main pod of the tower while tethered to an overhead rail system that allows them to walk around and over the edge of the building.