London's BT Tower was an official secret that a million visitors toured
In 1978 a judge ruled that London's tallest structure could be named in court only as Location 23. It was a strange order, since the tower had been visible from nearly everywhere in the city for years, and nearly a million people rode its lifts in the first year it was open to visitors.
The General Post Office commissioned the tower to hold microwave aerials carrying telephone and television traffic out of London. An older steel mast on the Museum Telephone Exchange, named for the nearby British Museum, was about to be blocked by planned high-rises, so something taller was needed. Architects Eric Bedford and G R Yeats of the Ministry of Public Building and Works chose a slim glass-clad concrete cylinder because it made a steady platform; even in 95 mph winds it moves no more than about 10 inches. The glass had to be tinted to stop the equipment overheating.
Building began in June 1961, and the crane perched on top became so conspicuous that an MP asked in Parliament in 1963 how it would ever be taken down. The tower was topped out in July 1964, and on 1 January 1965 its first microwave link went live to Norwich. It cost 2.5 million pounds and reached 177 metres, or 189 with its rigging, making it the tallest structure in London until 1980. Harold Wilson inaugurated it in October 1965.
Tony Benn and Billy Butlin opened it to the public on 19 May 1966. A revolving restaurant on the 34th floor turned once every 23 minutes, and more than 100,000 people dined there in the first year. A bomb in the restaurant in October 1971, claimed by the anarchist Angry Brigade, ended general public access, and Butlins' lease ran out in 1980.
The secrecy persisted into the 1990s. In 1993 Kate Hoey used parliamentary privilege to confirm that the tower existed and to give its address as 60 Cleveland Street. It became a Grade II listed building in 2003, gained a wraparound screen of 529,750 LEDs in 2009, and in 2024 was sold to MCR Hotels, which intends to turn it into a hotel.
Source: BT Tower
