| The CN Tower at 553.33 meters (1815 ft., 5 inches) was once the tallest building, tower, and freestanding structure, but as of 2010 retains the title of world's tallest tower. Construction on the CN Tower began on February 6, 1973 and wrapped up about 40 months later in June 1976. The CN Tower was built at an original cost of $63 million. On April 2, 1975, onlookers gazed up in amazement as a giant Erickson Air-crane Silorsky helicopter placed the final piece of the CN Tower's antenna into place, officially making it the world's tallest building. The CN Tower was built to withstand an earthquake of 8.5 on the Richter scale (the Kobe earthquake in 1995 was 7.2 on the Richter scale). The upper reaches of the CN Tower were built to withstand winds up to 418 km/h (260 mph). In 1995, the CN Tower is designated a Wonder of the Modern World by the American Society of Civil Engineers. Lightning strikes the CN Tower an average of 75 times per year. Long copper strips run down the CN Tower to grounding rods buried below ground to prevent damage. The CN Tower dims unnecessary exterior lights during bird migration seasons to prevent bird injuries. The CN Tower is an incredible 2.79 cm (1.1 inches) within plumb, or, true vertical. Six glass-faced elevators travel at 22 km/hour (15 miles/hour) to reach the observation deck in 58 seconds. On a clear day, visitors to the CN Tower's observation deck can see over 160 kilometers (100 miles) -- that's all the way to Niagara Falls and across ... |
