On this date in 1973 construction began on the CN Tower. The massive excavations required for the foundation began; 56,000 tonnes of dirt and shale were removed and replaced with approximately 7,000 cubic metres of concrete, 450 tonnes of rebar and 36 tonnes of steel cable. Four months later the foundation was ready for construction of the tower to begin and approximately 63 million dollars after that (about 243 million in current value) the tower opened its doors to the public on June 26, 1976.
Check out the photos below of the Tower under construction.