Experts have said the henge 'discovered' in Raunds has been known about since it was first unearthed back in the 1980s.
Winvic, who are currently carrying out work for the Warth Park expansion, tweeted a photo of the excavated ancient henge that archaeologists unearthed earlier this week.
The tweet has since been deleted, but has led to lots of discussion online about the site and the history of the henge.
Winvic’s tweet said: “Archaelogists on site at Warth Park, Raunds have discovered an ancient henge with an approximate age of 4000 years and spanning 100m in diameter.
“This aerial photo shows the scale of the Neolithic monument uncovered with its spaceship-like footprint.”
The Northants Telegraph has asked Winvic for a comment on the ‘discovery’ and why the tweet has been deleted, but has yet to have a response.
However, a spokesman for Historic England said: “To our knowledge a henge on this site was discovered back in the 80s (it isn’t a scheduled monument).
“We’re not involved in any current excavations and so unfortunately can’t shed any light on this for you and whether anything new has been found.”
Another expert in archaeology told the Northants Telegraph: “The henge being excavated has been known about for a considerable period of time, having been discovered on aerial photographs in the 1980s.”
A spokesman for East Northants Council, which approved plans to extend Warth Park, said: "The henge was known about prior to a planning application being submitted and, once we received an application for this site we consulted the Northamptonshire County Council archaeologist who is a statutory consultee in the planning process.
"One of the conditions imposed on the application as recommended by the archaeologist was that a scheme of works be developed that sets out how the developers planned to investigate and record their findings.
"This report was submitted and approved by the council in consultation with the archaeologist a year ago.
"The second part of the condition was that before any work starts the developers must fully investigate the site and report back to the archaeologist on their findings.
"The work that is currently taking place on the site is the archaeology investigation and not the start of building works.
"The archaeologist is in regular contact with the developers and is being consulted throughout the process.
"The final archaeologist’s report will be made available on our website once the investigation is complete and approved by the county archaeologist."
Warth Park is being extended after being granted planning permission last year, but the plans had attracted huge opposition from people in Raunds.
Campaigners who fought to stop the expansion lodged an appeal against the decision, but the application for a judicial review was refused.
The history of the site was one of their many reasons for opposing the plans.
This drone footage showing the henge was taken by BBC Radio Northampton.