Seven Modern wonders of the world

CN Tower

The CN Tower, located in Toronto, Ontario, Canada, is the world's tallest freestanding structure on land, standing 553.33 meters (1,815 ft 5 in) tall. It is considered the signature icon of the city, attracting more than two million international visitors annually.
CN originally referred to Canadian National, the railway company that built the tower. Following the railway's decision to divest non-core freight railway assets, prior to the company's privatization in 1995, the CN Tower was transferred to the Canada Lands Company (CLC), a federal Crown corporation responsible for real estate development. Since local residents wished to retain the name CN Tower, the abbreviation is now said to expand to Canada's National Tower rather than the original Canadian National Tower; however, neither of these is commonly used.

Structure
The CN Tower consists of several substructures. The main portion of the Tower consists of a hollow concrete hexagonal pillar containing the elevators, stairwells and power and plumbing connections. On top of this is the 102 metre (335 ft) metal broadcast antenna, carrying TV and radio signals. There are two main visitor areas: the main seven-story deck level located at 330 metre (1,100 ft), and the higher Sky Pod (formerly known as Space Deck) at 447 metres (1,465 ft), just below the metal antenna. Between the two areas the structure is "bare" and the hexagonal shape can be seen, but below the main deck three large supporting legs give the tower the appearance of a large tripod. Confusingly, the main level used to be known as “SkyPod”, a name which now refers to the higher level.
The main level consists of several floors, some open to the public. At 342 metres (1,122 ft) is the Glass Floor and Outdoor Observation Deck. The glass floor has an area of 24 square metres (256 sq ft) and can withstand a pressure of 42 kg•f/cm² (600 psi). The glass floor consists of thermal glass units that are 64 millimetres (2.5 in) thick, consisting of a pane of 25 millimetres (1 in) laminated glass, a 25 millimetre (1 in) airspace and a pane of 13 millimetres (0.5 in) laminated glass. Some people experience acrophobia by walking out on the glass floor and looking down at the ground below. At 346 metres (1,136 ft) is the Horizons Cafe and the Look Out level, and at 351 metres (1,150 ft) is the 360 Restaurant, which completes a full revolution once every 72 minutes. Below these areas are the structure's microwave receivers in a large white donut-shaped radome, at 338 metres (1,109 ft).