The remains of a timber circle from more than 4,000 years ago have been uncovered by archaeologists in County Tyrone.
The timber circle was found by the Headland Group near Ballygawley in 2006/2007 as part of an excavation project linked to the A4 and A5 road improvements scheme.
Project Officer at Headland Archaeology, Kirsty Dingwall, said radiocarbon dating had confirmed it was from around the middle of the third millenium BC, "although some elements of it may be earlier".
"The specific use of timber circles are not well understood but it is thought that they were used as ritual sites, perhaps for feasting or for commemorating the dead," she said.
"The find is very significant for archaeology and for Northern Ireland in particular, as very few timber circles have been fully excavated.
"It might seem that stone circles are more common as they survive better, but we are learning more and more about this type of site and how widespread they were.
"The postholes containing the timbers were carefully excavated and the pottery and charcoal found on the site are now undergoing close inspection and analysis by the Headland experts to reveal more about the activities which took place in the timber circle.
"The results of the analysis will be submitted to the Roads Service in 2010."
She said it was "made up of two concentric rings of timbers focussed on a central area, which appear to have replaced an earlier series of large pits".
It "had a large monumental porch on one side with a line of substantial timbers along the front, which would have formed an impressive façade for anyone approaching the circle".
"The outer ring of the double circle comprised pits holding four posts in a square arrangement, which would themselves have pinned sections of wattle or planked walling in place," she added.
"As a result, we can be fairly certain that it would not be possible to see into the centre of the circle from the outside, unlike other timber circles elsewhere in the British Isles, or at stone circles such as Stonehenge in Wiltshire or Callanish in Scotland, where an observer would have had glimpses of the activity.
"As timber circles are generally thought to have some form of ritual importance, the issue of restricting the views of what was happening inside the circle is an interesting one."
Kirsty said the archaeological investigations undertaken as part of the A4 and A5 road improvements scheme were "currently undergoing post-excavation analyses and reporting which are likely to throw interesting new light on the prehistoric archaeological record of the area".
The Department for Regional Development said road construction would not be affected by the discovery of the timber circle remains.