<Table> <Tr> <Th_colspan="2"> CN Tower </Th> </Tr> <Tr> <Td_colspan="2"> Tour CN </Td> </Tr> <Tr> <Td_colspan="2"> CN Tower is the world's 9th tallest free - standing structure . </Td> </Tr> <Tr> <Td_colspan="2"> Location within Toronto </Td> </Tr> <Tr> <Th> Alternative names </Th> <Td> Canadian National Tower, Canada's National Tower </Td> </Tr> <Tr> <Th_colspan="2"> Record height </Th> </Tr> <Tr> <Td_colspan="2"> Tallest in the world from 1975 to 2007 </Td> </Tr> <Tr> <Th> Preceded by </Th> <Td> Ostankino Tower </Td> </Tr> <Tr> <Th> Surpassed by </Th> <Td> Burj Khalifa </Td> </Tr> <Tr> <Th_colspan="2"> General information </Th> </Tr> <Tr> <Th> Status </Th> <Td> Complete </Td> </Tr> <Tr> <Th> Type </Th> <Td> Mixed use: Observation, telecommunications, attraction, restaurant </Td> </Tr> <Tr> <Th> Location </Th> <Td> 301 Front Street West Toronto, Ontario M5V 2T6 </Td> </Tr> <Tr> <Th> Coordinates </Th> <Td> 43 ° 38 ′ 33.36" N 79 ° 23 ′ 13.56" W ﻿ / ﻿ 43.6426000 ° N 79.3871000 ° W ﻿ / 43.6426000; - 79.3871000 Coordinates: 43 ° 38 ′ 33.36" N 79 ° 23 ′ 13.56" W ﻿ / ﻿ 43.6426000 ° N 79.3871000 ° W ﻿ / 43.6426000; - 79.3871000 </Td> </Tr> <Tr> <Th> Construction started </Th> <Td> 1973 </Td> </Tr> <Tr> <Th> Completed </Th> <Td> 1976 </Td> </Tr> <Tr> <Th> Opening </Th> <Td> June 26, 1976 </Td> </Tr> <Tr> <Th> Cost </Th> <Td> CDN $63,000,000 </Td> </Tr> <Tr> <Th> Owner </Th> <Td> Canada Lands Company </Td> </Tr> <Tr> <Th_colspan="2"> Height </Th> </Tr> <Tr> <Th> Antenna spire </Th> <Td> 553.3 m (1,815.3 ft) </Td> </Tr> <Tr> <Th> Roof </Th> <Td> 457.2 m (1,500.0 ft) </Td> </Tr> <Tr> <Th> Top floor </Th> <Td> 446.5 m (1,464.9 ft) </Td> </Tr> <Tr> <Th_colspan="2"> Technical details </Th> </Tr> <Tr> <Th> Floor count </Th> <Td> Equivalent of a 147 story building </Td> </Tr> <Tr> <Th> Lifts / elevators </Th> <Td> 9 </Td> </Tr> <Tr> <Th_colspan="2"> Design and construction </Th> </Tr> <Tr> <Th> Architect </Th> <Td> WZMH Architects: John Andrews, Webb Zerafa, Menkes Housden </Td> </Tr> <Tr> <Th_colspan="2"> Website </Th> </Tr> <Tr> <Td_colspan="2"> www.cntower.ca </Td> </Tr> <Tr> <Th_colspan="2"> References </Th> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> CN Tower </Th> </Tr>

When did they start building the cn tower