The signalling cabin at Edgware Road on the Circle and Hammersmith & City line has been designated as an item of national historic interest by the Railway Heritage Designation Advisory Board.
Originally built in 1926 and operated by the Metropolitan Railway — the world's first underground railway and the predecessor to LU — the cabin's technology is still in use today.
It is hoped the cabin will be opened to the public shortly after it is retired for signalling modernisation work.
Its mechanical "K-style" lever frame operates the interlocking of signals and points at the complex junction used by the Circle and Hammersmith & City lines. A signalling operator controls the system, with its many brass levers and interlockings, so that trains can arrive and depart on time.
LU is introducing new technology meaning trains can run more frequently and the system at Edgware Road will be upgraded as part of this.
Once completed there will be trains every two minutes across much of this part of the network in central London.
Mark Wild, London Underground’s Managing Director, said: "Upgrading the Circle, District, Hammersmith & City and Metropolitan lines will enable us to increase capacity for millions of our customers.
"At the same time, it's important to us that we recognise the significance of earlier technological advances made by London Underground.
"When the Edgware Road signalling cabin is honourably retired as part of our modernisation programme, it will have been in use for nearly a century.
"We aim to provide safe public access to the cabin in the future so the public can share this unique part of the capital's transport history."Full details of when the cabin could open are yet to be finalised. Watch this space.