Coming out of London Bridge tube station onto Tooley Street, you will often be buffeted from side to side by the hordes of tourists, and almost as many sales people trying to harangue you into visiting one or other of the two local horror shows.
If you are heading over to the Hays Galleria, then it can be a bit of a pain to squeeze though all the crowds, although regular visitors will know of how to use the side streets to escape.
What fewer know about is the underground passageway that runs right into the centre of the Galleria.
There is a footbridge over the road, and if you look next to where it comes down to street level you might notice another small set of steps leading down, often signposted as heading to a local gym. This is the tunnel.
Otherwise, hardly anyone comes down here, and few walk through from one end to the other.
The modern end is all glass and marble and very 1980s, then there is a carpeted tunnel running up to the faux-heritage brick arches underneath the Galleria itself.
I found out about the tunnel many years ago, as there are public toilets here, and are free, so make a useful service in the area where most other loos charge for use. They seemed to close for a few years, but are open again now.
What people popping downstairs to use the loo will rarely do though is wander off to see what the rest of the basement is like – although that is usually the first thing I do when I see an inviting doorway or corridor.
That lack of curiosity is what probably killed off plans to have more shops down here, and turned it into a bit of a secret that is a delight to show to often very surprised friends if you are in the area.
Is it that useful as a short-cut, well, no not really. But it is diverting.