Fragments of cremated human bone believed to date back thousands of years are among the discoveries after archaeologists unearthed the "find of a lifetime" - a 5,500-year-old passage tomb at the Bru na Boinne World Heritage site.
The "accidental" discovery of the megalithic cemetery on the grounds of the sprawling Dowth Hall estate in Co Meath was like winning the Lottery, according to lead archaeologist Dr Cliodhna Ni Lionain.
"It was completely unexpected," she told the Herald.
"It's definitely one of the most significant finds in the past 50 years. This is a huge deal that we found this passage tomb that no one knew existed.
"It's something that no one thought would be found at this stage. I don't think anyone dreamed of finding an unknown passage."
The exciting discovery was made last year as a team of archaeologists from the UCD School of Archaeology and agri-technology firm Devenish were conducting excavations on the grounds of the 18th century demense owned by Devenish chief executive Owen Brennan.
Mr Brennan, who bought the 420-acre site back in 2013 and is in the process of restoring the mansion, was required to conduct an archaeological assessment of the site.
When they began digging under a landscaped garden near the house, hidden about a metre below ground was the passage tomb - over which a large stone cairn had been placed.
Further excavations over the past year revealed two burial chambers and six slabs of rock, or kerbstones, that form a ring.
One of the kerbstones was decorated with Neolithic carvings of spiral or circular motifs. It represents one of the most impressive findings of its kind in decades.
Then, last Friday, the team found what they believe to be fragments of cremated human bone, which could belong to our ancient prehistoric ancestors, Dr Ni Lionain said, adding there could be more surprises in store.
"We're just getting to the juiciest parts," she said.