
Archaeologist Joe Fenwick revealed a LiDAR (Light Detecting and Ranging) laser beam had been used to scan the ground surface to create a three-dimensional map, which revealed more than 30 monuments around Tara.
Using another technique -- described as taking an X-ray through the hillside -- archaeologists discovered the huge monument, a ditch stretching six metres wide and three metres deep in the bedrock. The ditch, circling the Mound of the Hostages passage tomb, separated the outside world from the ceremonial centre of Tara.
It was believed the ancient architects had also surrounded the ditch with a massive wooden structure on each side -- a version of Stonehenge -- on a large scale. Its sheer size meant a whole forest would have had to be cleared to build it. (Independant.ie)