The purpose of a mysterious tree house has long baffled locals and passers-by.
The wooden structure has stood for several decades on the side of the Hume Motorway near Menangle.
Many people would recall seeing the unusual and dilapidated structure when they went for a drive along the highway.
Menangle Community Association member Brian Peacock said there had been several theories to explain why the structure had been built.
“The landowner’s theory is the structure is a water tank,” Mr Peacock said.
“There have been many rumours. The real reason is still a mystery.”
In 2012, a columnist for Fairfax Media, Tim the Yowie Man wrote articles about structure and spoke to Marie Holmes, a Campbelltown and Airds Historical Society researcher.
Ms Holmes spoke with Annette Macarthur-Onslow, a descendant of the famous Macarthurs, who were the first settlers to work the land.
Ms Macarthur-Onslow said the structure was a water tank.
“Apparently it was used to store water from the nearby Nepean River for use in the property’s dairy and butter factory and for a time also serviced the Menangle township.” the article said.
“The tank held about 8000 gallons of water and the water was transported by an open wooden trough to where it was to be used. Unfortunately, the trough is no longer remaining.
“Annette also advised Marie that the smaller wooden structure on the western side of the freeway is a remnant of a slaughterhouse and was used to hang the meat.”
However not all believe this explanation.
Tim the Yowie Man said there were several theories about the origins of the tree house.
Wal Glennon, who grew up in the area, said it was a commentary box for the original Menangle showground and trots, and the trees were not there 50 years ago.
Tim the Yowie Man reported that Downer’s Maurice Lynch told him the site was an internment camp during World War II for enemy aliens, and the structure was a guard tower for the camp.
Chisholm’s Michael Kirby said the tree house was part of a theme park.
Others have said it was a guard tower on an army base, a surviving relic of a RAAF air defence system for Sydney during World War II or was used as sleeping quarters from the early days of working the land, and was elevated in an attempt to ward of the mosquitoes.
Another theory is the tree house was a slaughterhouse on the old Gilbulla Estate.
It could have also been a storage shed or fire tower, or a summer house built for a French winemaker.
The origin of the structure will probably always remain an inconclusive mystery.