The concept of the CN Tower originated from a 1968 Canadian National Railway desire to build a large TV and radio communication platform to serve the Toronto area, as well as demonstrating the strength of Canadian industry, and CN in particular. These plans evolved over the next few years, until the project became "official" in 1972. The Tower would have been part of Metro Centre (see CityPlace), a large development south of Front Street on the Railway Lands, a large railway switching yard that was being made redundant by newer yards outside the city. Key project team members were NCK Engineering as structural engineer; John Andrews Architects; Webb, Zerafa, Menkes, Housden Architects; Foundation Building Construction and Canron (Eastern Structural Division). Construction on the CN Tower started on February 6, 1973 with massive excavations at the tower base for the foundation. By the time the foundation was complete, 56,000 metric tonnes (62,000 short tons) of dirt and shale were removed to a depth of 15 metres (50 ft) in the centre, and a base incorporating 7,000 cubic metres (9,200 cu yd) of concrete with 450 metric tonnes (500 tons) of steel re-bar and 36 tonnes (40 tons) of steel cable had been built to a thickness of 6.7 metres (22 ft). This portion of the construction was fairly rapid, with only four months needed between the start and the foundation being ready for construction on top. http://en.wikipedia.org/wiki/CN_tower