In all, some £73 billion of gold is stored in concrete-lined vaults beneath the busy streets of central London. It never oxidises or tarnishes (so it doesn't need to be covered), although it does need the odd dust - by a cleaner who has been carefully vetted, no doubt.
The vaults are huge and include three disused wells. In fact, the floorspace is actually larger than that of the City's tallest building, Tower 42. Keys three-feet long are needed to open the gigantic vault doors.
They look ceremonial, like something used for a state occasion, but these keys are in fact entirely functional.
As they are inserted into the locks, the person attempting entry also has to speak a password into a microphone before the vaults are opened.
The Bank is, understandably, rather secretive about the precise details of the vaults. But the walls must be literally bombproof as they were used by bank staff as air raid shelters during World War II. The posters on the wall, depicting sunny climes, luxury cruises and happier times, have been preserved from that era.
As the world loses its faith in most investments, gold provides a primel sense of security.