CN Tower

The CN Tower is a communications and observation tower in Toronto, Canada, completed in 1976. Its height and distinctive concrete design made it a landmark of the city.

Concrete: A composite building material made from cement, water, and aggregates such as sand and gravel. The tower’s shaft and main structure are made primarily of reinforced concrete.
Broadcasting: The transmission of audio or video content to audiences through radio, television, or digital networks. Broadcasting is the infrastructure purpose that drove the tower’s construction.
Canadian National Railway: A Canadian railway company that operated the tower’s original development project. The tower’s initials derive from the railway company that commissioned it.
Toronto skyline: The visible arrangement of Toronto’s buildings and structures against the horizon. The tower has defined the city’s skyline since its completion.
CN Tower construction: The building project that erected Toronto’s CN Tower between 1973 and 1976. Its construction involved a continuously rising concrete shaft and extensive prefabrication.
Reinforced concrete: Concrete strengthened with embedded steel bars or mesh to resist tensile forces. Steel reinforcement helps the tall concrete shaft withstand bending and wind loads.
Radio transmission: The emission of radio-frequency signals to carry information through space. The tower’s height helps transmit radio signals across the Toronto region.
Toronto broadcasting reception problem: Interference and signal-shadowing problems that affected television reception in Toronto as buildings grew taller. These reception difficulties supplied the practical case for a very tall broadcast structure.
World’s tallest structures: Structures ranked by height, including towers, masts, buildings, and other tall constructions. The CN Tower held the record for the world’s tallest freestanding structure for decades.
CN Tower antenna mast: The steel mast at the top of the CN Tower that carries broadcast antennas. The mast completed the tower’s height and provides a platform for transmission equipment.

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Ostankino TowerCompared with: The later Canadian tower surpassed Ostankino in height and became a comparable city landmark.