Archaeologists have discovered what is believed to be a prehistoric ceremonial site on Cave Hill in north Belfast.
It follows a community excavation involving more than 400 people at the site of Ballyaghagan cashel on the Upper Hightown Road, which had never before been unearthed.
Dr Harry Welsh, an archaeologist with Queen's University, which led the Big Dig project, said some of the earliest items on the site dated back to 3,500 years BC.
He said:"Before we started the dig we thought there would be no big mystery.
"It was a cashel and we would just be in and out again.
"But after a few days we started to see that this site does not conform to all the features of a cashel.
"The medieval lecturers at Queen's are especially excited by what has been found.
"We started off and we thought we would have an early Christian enclosure, and there's an enclosure, but nothing really early Christian so that is interesting.
"The other feature of the site is a small cottage which we thought was 19th century but is actually much earlier than that, so we have had a fantastic time finding all these new things."
Dr Welsh also drew attention to a piece of sandstone which was uncovered at the site and has been inscribed with a unique design.
"We have a piece of sandstone and someone has gone to the trouble of inscribing an oval shape on it with segments, very like if you took a cross section of an orange," he added.
"It is on both sides, so the jury is out on this one.
"This is really unique, you really don't find these things. It could be a gaming piece or a child scratching a rock, we won't know until we get it off for analysis."
Dr Welsh said the site was important as it brought us nearer to the community who would have lived on the hill many centuries ago.
""The important thing for all of us is not so much the stones, it is the people," he said.
"These were people who lived up here, people who built the cottage, who built the cashel, like us.
"It is a connection we now have with the people of the past."
The project was spearheaded by the Belfast Hills Partnership.
It was one of a series of schemes earmarked for a £1.7m Heritage Lottery Fund landscape partnership scheme in the Belfast hills.
The Northern Ireland Environment Agency and Belfast City Council, which owns the land, also funded the project.