When the CN Tower was built in 1975 at a cost of $333 million 2025 dollars, to a height of 1815 feet, it was the tallest free-standing structure for 32 years. when in  2007, the Dubai Burj Khalifa was completed.  CN T remained as the world's tallest tower until 2009 until it was surpassed by the Canton Tower, and is now #10.  To the right. the Burj Khalifa, CN Tower and Willis Tower ( Chicago ).  CN T is the signature icon of Toronto's skyline, and draws 2 million international visitors/year. The CN stands for Canadian National, the railway that built the structure; When opened in 1976, there were three observation points:  The Top at 1,467 feet, the Main Observation Level at 1,135 feet, and the Terrace, the one with the glass floor, at 1,122 feet. One floor above the Observation Level is 360 The Restaurant at the CNTower, which completes a complete rotation every 72 minutes. In 1995 was named by the American Society of Civil Engineers as one of the modern Seven...