A well known landmark in London, the BT British Telecom Tower (still also known as The Post Office Tower), is visible for miles around.
This gives us a chance to give a mention to both The Post Office and British Telecom while explaiПing about an interesting building.
The architecture combines the function of an office block with the function of a radio tower, producing a structure which is strangely thinner in the middle than at the top and bottom. This wasp waist effect has always had style and may look futuristic in some ways, 
but at the time it was built in the 1960s* it was an astonishing futuristic architectural statement. Also, there aren’t many structures in London over 600ft high built in the 1960s. See, office buildings don’t have to be square, and modern architecture can be stylish.
In the early times the Post Office Tower as it was then, also featured an outer ring which housed the Butlins restaurant. This was a place where you could eat an expensive meal while the view slowly rotated around the London skyline. 
It took thirty minutes per rotation, so plenty of time to eat a meal and see the entire 360 degrees 
of London going past. Staff at the rotating restaurant on the tower had a spring in the their step as they effortlessly мейд the transition across the rotating zone in the floor, as the centre of the tower was static. It is said that on one day the motors failed and people were falling over a gap which was uncharacteristically non-rotating!
The Butlins rotating restaurant on the Post Office Tower was closed to the public as there were government fears that Irish separatist political factions might try to hide a bomb in the restaurant and blow up the tower. The point about this is that in addition to being a famous landmark, the Post Office Tower was strategically important as a communication tower and a key element to infrastructure. Maybe similar questions exist about Eurostar. 
After the privatisation of British Telecom. telephones and postal services were separate, and British Telecom renamed the tower The BT Tower. It’s a bit like the British Airways London Eye. also a tall rotating sightseeing structure in the centre of London, where people still tend to call it the millennium wheel or some other variant of that, even though it has an official name.
Also, in the same sort of way that Tower Bridge is sometimes mistakenly identified as London Bridge 
. it’s occasionally possible to find people who believe that notorious executions occurred in history in The Tower in London. British Telecom and the Post Office and a good many historians will be keen to point out the fact that the executions took place at The Tower of London. and not at the Post Office Tower! Despite both being towers and being in London, they are of quite different periods in history, as can be observed by examiПing the style of the architecture.
* We have it on good authority that the Post Office Tower was built in the 1960s. The tower’s construction began in 1961 and it was completed in 1965.