The site is seen as being so important that a team of over 30 archaeologists is currently working to unearth its secrets.
The Drumclay Crannog, as it is known, is on the route of the new Enniskillen by-pass, between the Cherrymount Roundabout on the Irvinestown Road and a newly constructed roundabout on the Tempo Road.
Work on the road has been delayed and it is now not expected to be completed until next March, a year behind schedule, although two stretches are due to open before Christmas.
The joint contractors, P. T. McWilliams and McLaughlin and Harvey, are to be paid compensation for the additional work and delay caused by the archaeological dig.
A crannog is a type of ancient lough dwelling. Most are circular structures that seem to have been built on artificial islands as individual homes to accommodate extended families.
The excavation of the Drumclay Crannog is being undertaken on behalf of the Historic Monuments branch of the Northern Ireland Environment Agency.
The Medieval site, at least 700 years old, has already revealed evidence of its timber-and-soil construction, as well as a wicker-walled structure, possibly a house. It has also produced fragments of mill stones, wooden plates, small crucibles for metal-working, vast quantities of pottery and even pieces of cloth and part of a wooden plough. Some human remains were discovered, though it is thought that this was not their original burial place.
Two arrowheads found on the site, and dating to 3,000 or 4,000 years ago, were probably brought in accidentally with soil to build up the crannog.
A spokesman confirmed: "There have been a number of significant discoveries at the Drumclay Crannog excavation which are reshaping our understanding of medieval life at these kinds of sites. At present there is a team of over 30 archaeologists on the site, and this team has made rapid progress in excavating and recording the site. At present the archaeological excavation is scheduled to end on December 30, 2012. Officials are currently making arrangements for an open day at the site where the public will get the opportunity to see some of what has been found. It is hoped to arrange this within the next two weeks."
The archaeologists are working against the clock as the dig is holding up construction of the new by-pass.
A spokesman for the Department of Regional Development's Roads Service said: "Given the complexity and significance of the finds made to date, the time period for excavation of the crannog has been extended on three occasions and it is currently anticipated that the dig will stop at the end of December; a total duration of 28 weeks. In this regard, the Historic Monuments branch within Northern Ireland Environment Agency and Roads Service continue to work in partnership to ensure that the excavation of the crannog is brought to a satisfactory conclusion at the earliest possible time.
"Whilst the contractor has accommodated the archaeological dig and has progressed other areas of the works, the excavation of the crannog has impacted on cost and the time to complete the works. Despite this, construction work on sections of the new road are at an advanced stage and it is hoped to open parts of the new road to traffic in advance of full completion of the works. It is anticipated that the sections between Coa Road and Tempo Road and also between the Irvinestown Road and Carn Industrial estate will be complete and available to traffic prior to the Christmas break. The archaeological dig is due to stop in December and it is anticipated that the remaining section of new road between Coa Road and Carn will be completed and available to traffic in March 2013," he added.
"The contractor has accommodated the dig and been in attendance as and when required by the archaeologists. There will inevitably be additional costs associated with attendance, and the delay and disruption caused by the resolution of the crannog. The value of the additional costs owing are yet to be agreed with the contractor," the spokesman explained.