The Recumbent Stone Circle has been recorded on a farm in Aberdeenshire, in the parish of Leochel-Cushnie.
The complete stone circle has been known and respected by those farming the area over time but the ancient formation has been unknown to archaeologists until now.
The site, which sits between Aboyne and Banchory, has now been recorded after it was reported to Aberdeenshire Council’s archaeology service by Fiona Bain, whose family have farmed in the area for generations.
Experts from the local authority and Historic Environment Scotland have now visited the site and believe the stone circle is a slightly unusual example of its kind.
Neil Ackerman, Historic Environment Record Assistant at Aberdeenshire Council, said: “This amazing new site adds to our knowledge of these unique monuments and of the prehistoric archaeology of the area.
“It is rare for these sites to go unidentified for so long, especially in such a good condition.
“To be able add a site like this to the record caps off what has been a fantastic year for archaeology in north east Scotland.”
Adam Welfare, of Historic Environment Scotland, said the circle, made up of 10 stones, was smaller in diameter than other similar examples with the individual stones proportionately smaller than usual.
The circle “enjoys a fine outlook” with its rich lichen cover “indicative of the ring’s antiquity,” Mr Welfare added.
Recumbent Stone Circles were constructed around 3,500-4,500 years ago and are unique to the north east of Scotland.
Such stone circles are defined by a large horizontal stone - the recumbent - flanked by two upright stones, which are usually placed to the south-east to south-west of the circle.
Recumbent stone circles are well known and spread throughout the north east of Scotland, but it is rare to find a previously unrecorded one, especially in such a complete condition.
This newly-recognised stone circle will add to the understanding of this period of the prehistory of north east Scotland and of these remarkable sites, a spokeswoman for Aberdeenshire Council said.
Moira Ingleby, chair of the Marr Area Committee at Aberdeenshire Council, said: “This newly recorded site highlights the internationally important archaeology we have within Aberdeenshire.
“Adding it to the record of known archaeological sites will add to the understanding of these fantastic monuments that are unique to the area.
“Its identification highlights the importance of having archaeologists based at the Council who are able to work within the community and pick up on this local knowledge.”