(CNN) — When a Stonehenge-like stone circle was discovered on farmland in rural Scotland last year, archaeologists were thrilled.

Recumbent stone circles, like the new discovery, were built between 3,500 and 4.500 years ago and were unique to the northeast of Scotland, Aberdeenshire Council wrote on its website at the time.

"This amazing new site adds to our knowledge of these unique monuments and of the prehistoric archeology of the area. It is rare for these sites to go unidentified for so long, especially in such a good condition," Neil Ackerman, the council's historic environment record assistant, said in its statement.

But excitement turned to embarrassment in January, when the former owner of the farm where the circle was found approached the council to let it know he had built the monument himself in the 1990s.

Responding to the news, the council said research into the site had been "cut short."

"These monuments are notoriously difficult to date," said Ackerman in a statement on the council's website. The council said the find was considered unusual at the time of discovery because of features that included its small diameter and proportionately small stones.

"There is however a huge amount of variation between recumbent stone circles, so finding these kinds of differences was not initially a major cause for concern," it said.

"It is obviously disappointing to learn of this development, but it also adds an interesting element to its story," said Ackerman. "I hope the stones continue to be used and enjoyed -- while not ancient it is still in a fantastic location and makes for a great feature in the landscape."

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According to Scotland's Forestry Commission , recumbent stone circles get their name because one large stone in the circle is laid on its side. Up to 99 examples of recumbent stone circles have been found in Scotland.