The cross formerly stood on a large boulder on Roughan Hill, 2 km (1¼ mile) northwest of Kilnaboy; but was later moved several times for safe-keeping, lastly to Clare Heritage & Genealogy Centre in Corofin, where it is now located.

[7] In 1937, Adolf Mahr, Keeper of Irish Antiquities and Director of the National Museum of Ireland, published a theory that associated the cross with the Celtic double-heads from Roquepertuse, France.

In 1940, Joseph Raftery supported this theory, counting the Kilnaboy cross in the same category of La Tène sculptures.

Etienne Rynne, however, in an article on the Tau Cross in 1967, compared the craft style of the two carved heads with other works nearby – the immediate area offering three other examples of tau-croziers.

He thus showed that the cross was in fact likely a boundary mark of the Romanesque period (12th century) and not a pagan idol of the early Iron Age.