For nearly 700 years, the Uí Néill stronghold was the Grianan Aileach, a massive ring fort still standing atop Greenan Mountain, five miles west of modern day Londonderry (Derry): Curiously, part of Niall’s story occurred in England in 1919.
That year, archeologists discovered a hoard of Roman silver, dating from Emperor Valens (365-378 A.
Keating states that Niall died a pagan, but after the spread of Christianity in Ireland, his descendants (the Uí Néill) became foremost in promoting and endowing the early Christian Church in Ireland; and nearly 300 of them were canonized as saints.
He was the founding ancestor of the great Uí Néill (O’Neill) royal dynasty that would control most of Ireland for the next 1200 years as kings, chieftains, earls, abbots and bishops.
According to legend: “Young Niall had to survive the malice of his wicked stepmother, Mongfhinn, who left him naked upon a hillside to die.