The long abandoned Post Office Railway is to start tours from July, with tickets going on sale next month.
A specially commissioned little railway carriage has been built to carry passengers on a looping trip around part of the mothballed tunnel network as part of a larger museum of postal history.
The tours will include the maintenance depot area at Mount Pleasant, near Farringdon, then a journey down into the tunnels themselves.
To be on the mailing list to be told when tickets go on sale – register here.
For a teaser of what’s down there, photos from a previous visit are here.