How old is the hill of Tara?

It's impossible to give a definitive age for the Hill of Tara. It's been a site of human activity for thousands of years, with evidence of occupation dating back to the Neolithic period (around 4000 BC).

However, the "hill" itself is likely much older, formed naturally by geological processes over millions of years.

Therefore, we can say:

* The site of Tara has been inhabited for at least 6,000 years.

* The hill's formation is much older, predating human occupation.

It's more about understanding Tara as a site with a long and layered history, rather than a single, easily quantifiable age.