By Victoria Bartlett
BBC Hampshire & Isle of Wight
Fort Widley tunnels are where most of the ghosts sightings are reported
In the 19th Century, it was feared that the French would invade the southern coast of England.
Then Prime Minister, Lord Henry Palmerston, called for a review of the defences of Portsmouth.
Fort Widley was part of "Palmerston's Folly" - a civil defence across Portsdown Hill built in 1861 to defend the city from sea and land attack.
The Victorian fort has had numerous reported sightings of ghosts over its 140-year history.
History of Fort Widley
The barrack block of Fort Widley on Portsdown Hill
The enormous structure is surrounded by a dry moat with mortar batteries in case anyone tried to enter the moat. These are accessed from tunnels deep underneath the parade ground.
There was enough accommodation for 250 men and there were 12 married quarters as well.
The six-sided building was completed in 1870 at a cost of £93,980.
Fort Widley was one of six forts, built at great expense, but by the time they were finished the threat of a French invasion was gone.
The forts on the crest of the hill overlooking the city and harbour also face inland and so, it is thought, they look the wrong way.
It was disarmed in 1907 but remained in military hands being used as a barracks for the Royal Artillery until 1939.
A spiral staircase from the parade ground accesses the four main tunnels
During World War II Fort Widley was used for planning rooms and as the Royal Engineers' Bomb Disposal Unit.
In 1942 it was used to house prisoners of war and from 1943 it was an alternative control centre for Southwick House (HMS Dryad).
Then on 19 February 1952, the Civil Defence Committee of Portsmouth Borough Council proposed the construction was needed for the borough to be used in the event of a nuclear attack; it was decided this should be established at Fort Widley.
It continued to perform this function until the end of the Cold War and the Portsmouth District Council Emergency Centre, as it was by then known, finally closed in 1992.
Spirits of Fort Widley
Jonathan Fost leads ghost investigations at Fort Widley
It is these underground chambers that most of the paranormal activity is said to have been experienced.
Ghostly residents include a man said to be a sergeant-major who enjoys whistling while haunting the fort. The old sergeants' mess is reported to be a very intimidating area to visit now.
The keep of the fort is another area where there have been reports of ghostly footsteps and bangings are often heard. These are said to be made by a former prisoner, or possibly a prison guard.
There are reports of the spirit of a little boy haunting the tunnels that run deep beneath the fort. It is said that he was a drummer and was being pursued along the parade ground by a superior officer, having been disobedient, and fell to his death down the spiral staircase.
Rapid footsteps have been heard running along the tunnels and, apparently, he often plays games.
Ghost hunters have detected a very dominant male spirit and say they feel a sense of foreboding when he approaches. He has been sighted walking with a lantern and peering over people as a 7ft (2.13m) tall dark shadow.
A female spirit is said to be the wife of one of the married couples that resided at the fort or one of the prostitutes that came up to the fort to cater for the male occupants.
The story says she was murdered there and her tormented spirit is always trying to flee her aggressor. It is also said that she looks after the spirits of the children found within the tunnels.
The fort was bought and restored by Portsmouth City Council in 1972
Dark Encounters run ghost hunting evenings including a vigil within the dark tunnels that go deep within the chalk hills of Portsdown, where there are plenty of areas to explore and investigate.
Jonathan Fost runs these investigations: "The tunnels are so atmospheric and it is a fantastic location for paranormal activity. They were probably used for smuggling from the dockyard at some point and this is where people tend to feel something spooky."
Matt Hall from Southampton enjoys ghost hunting at Fort Widley: "My friends don't see this as a normal activity but I love it.
"I have seen half a body from waist upwards when I was taking down cameras at the end of an evening in the tunnels. I saw it only briefly but it was enough to make me run to the top!
"It's amazingly addictive and I get such an adrenalin rush from it."
Debbie Hickman has also taken part in spooky events at Fort Widley: "When I was down here with my sister doing a vigil we saw two sets of legs walking down this tunnel with a candle and then they turned off into the wall.
"For me it's proof that there is something after this life - the things that I have seen and heard are not just my imagination."
For more information about the ghost investigations held at Fort Widley go to the