This ancient ritual and burial mound is the oldest visible monument on the Hill, dating back to about 2,500 B.C. Just inside the entrance to the left can be seen the engraved stone. Its symbols relate to the sacred Celtic festivals and are thought to have images of the sun, moon and stars. They may have had an even deeper religious meaning than that to the person or persons who chiselled them thousands of years ago.
The name Mound of the Hostages derives from the custom of over- kings like those at Tara retaining important personages from subject kingdoms to ensure their submission.
One of the legendary kings of Tara was named Niall of the Nine Hostages in recognition of the fact that he retained hostages from all the provinces of Ireland and from Britain - one each from the central kingdom of Meath and the other four provinces of Ireland plus four from Britain. Niall is the founding ancestor of the O'Neill dynasty that had 28 kings rule in the name of Tara between 400 and 1022 A.D.
Tara’s Ancient Anthropology
Extensive excavations were carried out at the Mound of the Hostages between 1955 and 1959.
It was found to contain more than 200 cremated or inhumed burials. Some of the cremated remains were placed under upturned earthenware urns along with burial gifts. Different types of urns relating to the burial customs of the peoples that successively inhabited the area around Tara between 2,000 and 500 B.C. were found in stone cysts created around the edges of this mound.
Professor Ruaidhrí de Valera then wrote "the mound yielded the most comprehensive series of grave goods yet available from any example in Ireland."
Also found in the mound was the skeleton from the Bronze Age inhumed burial of a fourteen year-old boy. Around his neck were the beads of a very decorative necklace made from bronze, amber, jet and faience. This young man must have been a person of great importance.
Recent archaeology investigations by the Discovery Programme at Tara have revealed the underground presence of a huge henge circle which some 5,000 years ago encompassed the whole top of the hill.
It appears to have been a wide three meter trench with rows of large posts erected at a distance of one meter on either side of it - if reconstructed now it would be a very imposing monument that would bear a resemblance to that of Stonehenge.
From The Tara Walk by Michael Slavin, edited for emphasis