In 1975, the final portion of the antenna atop Canada's CN Tower was set in place, completing the tower and officially making it the tallest free-standing structure on land. At 1,815 ft (553 m) in height, the CN Tower surpassed the previous record holder, Russia's Ostankino Tower, by 43 ft (13 m) but was itself surpassed in 2007 by Dubai's Burj Khalifa. According to a study, the CN Tower is struck by lightning more than any other structure in Toronto. How many times is it struck each year? Discuss (http://forum.thefreedictionary.com/postst15264_CN-Tower-Becomes-World-s-Tallest-Free-Standing-Structure--1975-.aspx)
Source: CN Tower Becomes World's Tallest Free-Standing Structure (1975) (http://encyclopedia.thefreedictionary.com/CN+Tower)