Construction for Sydney's new metro train line has uncovered two 'ghost platforms' hidden beneath Central Station, buried and abandoned for 40 years.

Platforms 26 and 27 lie dormant and gathering decades of dust as 270,000 people walk above them every say without knowing what lies beneath their feet.

They were built in 1979 on the site of the Devonshire Street Cemetery as part of the Eastern Suburbs Railway line for Bondi and Illawarra but never completed.

Bodies lying in the graveyard were reburied across the city decades earlier but workers claim to have claimed to hear voices echoing against the walls, and even the sound of children playing.

Now linked to the new tunnels, the ghost platforms will finally be put to use housing 17 new communications and power rooms for the metro line when it is finished.

Urban explorers have for years found creative ways of checking out the disused platforms, evidenced by the graffiti lining some of the walls and columns.

Lying between the eastern concourse and platforms 24 and 25, they can occasionally be reached via the lift to the Bondi to Cronulla platforms if a worker has left the button active.

Rail historian John Oakes said there were many stories about people either feeling or hearing ghosts after coming down to the abandoned platforms. 

'Sometimes they might feel a hand on their shoulder and look around and there is nobody there. They are very eerie places,' he said.

The disused platforms also connect to a labyrinth of tunnels underneath Central Station and surrounding areas 

One secret entrance is a nondescript metal door in the carpark of an office building on Pitt Street, behind an electrical substation. 

'The entrance to this particular tunnel is near a loading dock in an underground carpark behind an electrical substation,' a former train worker previously explained to Daily Mail Australia. 

'It's used mainly these days for cleaners and freight, it's also a shortcut for the drivers and other train workers.'

'There's also a locked vault with a steel door in this tunnel, no one is allowed through the door and no one knows what's in there.

'It's a bit unnerving if you're in there for long periods of time.'

Among the tunnels are an abandoned station master's office, complete with fireplace and federation doors, and bathrooms and workspaces frozen in time. 

Sydney Trains operations director Tony Eid also claims to have heard the sound of children's voices on a visit to station's never-used tunnels.

He previously told the Sydney Morning Herald: 'Workers down here said they would hear kids playing and, thinking they were vandals, would go and investigate.

'On one occasion I was down here with a radio crew and we all heard children playing. Take that as you wish but we all heard it'.

Aside from the station's ghostly past, it is also the site of more tangible historical events like the Battle of Central Station - where soldiers rebelling against the army were involved in a shootout with military guards.

One stray bullet hole near platform one is what remains of the exchange started by a drunken soldier's gunshot - which led to the guards killing one and injuring eight when they returned fire.

St James station also has ghosts platforms, numbers 1 and 2, and a series of off-limits tunnels underneath the concourse and nearby Hyde Park. 

They contain a former bomb shelter and, surprisingly, an underground lake.

A photographer and several associates recently sneaked into the tunnels, many of which were flooded and some were just inches from passing trains.

Ghost hunters at Macquaire Fields train station in the city's southwest also claim to have seen a ghostly apparition clutching her bloodied chest and shrieking in terror.

Others claim to have heard a 'faint crying on the breeze' late night following the departure of the last train.