BT Tower's cylindrical design allows for a precise 360 degree placement of telecommunications apparatus and its minimal sway is intended to minimise disruption to these instruments.
The 34th floor was built incorporating a revolving restaurant (originally known as The Top of the Tower), which completed a full rotation every 22.5 minutes.
The telecommunications array comprises 57 microwave aerials; the horn-style aerials are now redundant but are too large to make removal practical.
The foundations descend to a depth of 6 metres (19.6 feet) and a reinforced steel concrete raft supports a truncated concrete pyramid measuring 27 metres x 27 metres x 6.5 metres (88.5 feet x 88.5 feet x 21.3 feet) on top of which sits the tower.
The revolving restaurant's floor section is 3.35 metres (11 feet) wide and rotates at 0.17 miles-per-hour powered by an electric 2 brake horsepower motor; the restaurant was run by Billy Butlin of holiday-camp fame.
The BT Tower (formerly Post Office Tower) was London's second tallest structure until the completion of One Canada Square in 1991.
Despite being a major London landmark, until the mid-1990s the tower did not officially exist and was not marked on Ordnance Survey maps.
Although the BT Tower is technically a TV Tower, it does have regular internal floors for part of its height. The first 16 floors contain radio, ventilation, refrigeration and power units, above which is a 35m section containing microwave antennae, aerials and dishes for telecommunications transmissions.
The building was the first-ever purpose-built telecommunications tower of its type and helped obviate the need for laying telephone cables.
Around 50,000 square feet of glass encase the tower's concrete shaft.
The elevator car's interior is visually very high-tech with flat-screen indicators and a graphic of the tower, cut by laser which features blue LED bars which rise and fall showing the elevator's relative position in the tower.
'Demolished' by Twinkle the giant white kitten in an episode of BBC TV's The Goodies titled 'Kitten Kong' of 1972.
The shape and tinting of the building were chosen to minimise the effects of an indirect nuclear blast.
The tower is the hub of Britain's terrestrial television broadcasting.
Ascending the height of the tower in 20 seconds at 7 metres per second, the new elevators (which were installed in 2000) are amongst the fastest in Europe.
The original cost of construction was £2.5m.
The height of the tower was dictated by the need to broadcast signals over the Chiltern hills which form the north rim of the London basin.
The tower houses a Mediahive digital content management system with a storage capacity of 3.6 petabytes.
The actual tower is a hollow concrete shaft from which the floors hang.
The 6 floor rotunda at the top of the tower contains the presentation and function rooms (known as the Tower Suite), kitchens and more technical facilities, and the whole structure is topped by lift motors, water tanks and a weather radar aerial.
Originally there was a rotating boomerang-style storm radar and lattice mast at the top; today the storm radar no longer exists.
The tower is designed to sway by as much as 38 centimetres (15 inches) in a 175 kilometres-per-hour (110 miles-per-hour) wind.
The BT Tower was topped out on 15th July 1964, became operational on 8th October 1965 and received its public opening on 19th May 1966, conducted by Anthony Wedgwood Benn (Tony Benn) who was the Postmaster General.
The tower is Europe's most complex and largest video switching centre, carrying out around one million switches per annum.
There are 95 tonnes of high tensile steel in the base, 695 tonnes of mild steel in the structure and 13,000 tons of concrete.
Due to expansion and contraction caused by the cold of winter and the heat of summer, the tower's height varies by as much as 23 centimetres (9 inches).
The elevator car is one of Britain's tallest.
Arguably London’s most recognisable and iconic structure.
The restaurant was bombed by the IRA in 1971 but remained open until 1980, when the lease expired; it was refurbished opening in 1984 to British Telecom employees and guests only.
The BT Tower became a Grade II Listed building in 2003.
The revolving restaurant runs on nylon bearings and rollers.
In 2001 the tower was declared a national monument by English Heritage.
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