Winter solstice: Beaghmore, the Newgrange of the Sperrins just south of the Derry/Strabane district

Academics at Queen's University, Belfast, have described the Beaghmore Stone Circles, not far south of Park and Draperstown, as the "most extensive concentration of stone circles" in Ireland.

The ancient site, which was excavated between the 1940s and 1960s, consists of seven stone circles of different sizes and ten stone rows.

"All but one of the stone circles occur in pairs," researchers at the QUB Centre for Climate, the Environment and Chronology (Chrono) observed.

"The singular circle can be distinguished from the paired circles by its slightly larger stones. It is also unique in that the interior of the circle is filled with more than 800 small stones.

"These small stones, which have been placed upright within the circle are referred to as 'the dragon’s teeth'. Most of these circles have small stone alignments touching them at a tangent.

"In addition, the site includes a dozen small stone cairns, frequently covering a cremation burial. Each of the three pairs of stone circles have a small cairn placed in between.

"The site also consists of low banks of small stones running below, and possibly pre-dating, the other structures which may have been field walls in the Neolithic period," they add.

Today the shortest day of the year has been ceremonially marked in Ireland for thousands of years.

The spectacular passage of sunlight through the Newgrange passage tomb each December 21 is the most famous example of its importance but it's believed Beaghmore may have served a similar purpose.

The chronologists at Queen's reported: "The site could mark a focal point for religious and/or social gatherings. Some archaeologists conclude that the circles have been constructed in relation to the rising of the sun at the solstice, or to record the movements of the sun and moon acting as observatories for particular lunar, solar or stellar events.

"Three of the stone rows point to the sunrise at the time of the solstice and another is aligned towards moonrise at the same period. However, most of the remains at Beaghmore do not indicate very accurate alignments upon specific astronomical features."