Since March, Bush House has been emptying gradually. Region by region and floor by floor, the language services have been leaving. Now the move is complete, the building is silent and the lifts come unnervingly fast.
The central newsroom was the last to leave, waiting until midday on Thursday 12 July, when the final five-minute bulletin was read and the switch was complete.
I've been recording the memories of those who worked in Bush House. Many of our interviews have taken place in the bowels of the building, in the underground drama studio, originally a swimming pool when Bush first opened in 1925.
One of the oldest memories came from Leonid Finkelstein who worked in the Russian Service for nearly 30 years, but who first heard the BBC in one of Stalin's labour camps in 1948. His fellow prisoner there was an engineer, and managed to build a radio out of scraps of metal. One day he gave Finkelstein an ear-piece. "And that is how I first learnt about the Chelsea Flower Show in London," he says.
Yuri Goligorsky also listened secretly, as a child in Moscow. Every morning his father would close the windows to avoid detection and turn on the radio for the daily 06:45 Russian Service broadcast. Goligorsky told us how his family used to analyse what they had heard. "Long conversations ensued after broadcast, perhaps it was a 15-minute programme and then we had a two-hour discussion afterwards," he says.
Years later, when Goligorsky worked in Bush House, whenever he sat down at a microphone to broadcast, he had only ever had one listener in mind - "always a picture of my dad," he says.
It was Goligorsky who masterminded one of the landmark broadcasts from Bush House. In 1988, he sent a letter to Downing St, asking if Mrs Thatcher would take part in a live phone-in to the Soviet Union.
It was the first time anything like it had been attempted - there was no direct dial to the UK from the USSR, every international call had to be booked through an operator. Goligorsky's sleepless nights ended in triumph, however - they had more than 800 calls from Russia, so many so that the telephone exchange in Covent Garden was overloaded.
The Daily Mail ran a cartoon about it, showing two burly prison guards at a salt mine somewhere in Siberia dangling a scrawny dissident between them. The caption read: "Was it you who booked a call to Mrs Thatcher?"
Many of the stories we heard about Bush House centred on the canteen - the melting pot of Bush House. I remember it at lunchtimes as a kind of friendly but overwhelming Babel, each table occupied by a different language service all competing to be heard in the cavernous underground room.
At its peak, the World Service was broadcasting in 45 different languages from Bush House, which allowed for some fairly niche specialisms - a Welsh service transmitting to Patagonia, and Portuguese for Jersey, targeting all the ex-pat hotel staff who worked there.
Graham Mytton, who was head of the Hausa section, remembers receiving letters addressed to The Queen, c/o Bush House, and once a sole envoy from Hadeija in northern Nigeria arrived at reception asking for the Hausa service.
He'd been sent by the Emir to buy hospital equipment in the UK, and upon landing at Heathrow, only knew one building in London to go to. Mytton took him on to the Department of Trade.
Now as I leave Bush House myself, it's the sounds from the building which will stick in my memory - the female voice in the lifts announcing each floor in her peculiar but very familiar clipped tones.
Lillibulero, the World Service's signature tune, originally an Irish jig by Purcell - played so many times it must be impregnated in the walls by now. And finally the noises from the Strand, which so often came in through the windows as we worked - the traffic and sirens, but also the frequent demonstrations and noisy gatherings outside.
Bush House is on one of the main arteries into Trafalgar Square, and we'd often stop work to peer down at the protesters marching past shouting their slogans. After so many years and so many millions of spoken words broadcast from Bush House, now it waits in limbo for its new future, still filled with the ghosts and voices of the past.
Photographs by Bogdan Frymorgen. Audio by Emma Crowe. Music by Robin Warren and KPM Music.
Slideshow production by Bethan Jinkinson and Paul Kerley. Publication date 12 July 2012.