At 1805 feet tall, the CN Tower was the world's tallest freestanding structure. The lower 1500 feet were slipformed and required careful control of concrete strength during winter construction. Peter Smith and John Bickley developed a system to assure that the concrete gained sufficient strength with heated concrete, insulation for 37 feet below the slipform, and one of the earliest uses of maturity methods to monitor strength gain.

Take a look at other significant projects over the past fifty years in which concrete and industry innovations played a major role.