An old legend tells that Irish monks removed the relics of St. Nicholas from his shrine in Demre, Turkey to prevent them falling into the hands of the invading heathen hordes. So like many others (St. Valentine is buried in Dublin) Saint Nick became a Paddy!

The Bones of Santa Claus
Bill Watkins

Where lie the bones of Santa Claus
To what holy spot each pilgrim draws
Which crypt conceals his pious remains
Safe from the wild wind, snows and rains.

It's not in Rome his body lies
Or under Egypt's azure skies
Constantinople or Madrid
His reliquary and bones are hid.

That saint protector of the child
Whose relics pure lie undefiled
His casket safe within it's shrine
Where the shamrocks grow and rose entwine.

Devout wayfarer, cease your search
For in Kilkenny's ancient church
Saint Nicholas' sepulcher is found
Enshrined in Ireland's holy ground.

So traveler rest and pray a while
To the patron saint of orphaned child
Whose bones were brought to Ireland's shore
Safe from the Vandal, Hun and Moor.

Here lie the bones of Santa Claus 
Secure beneath these marble floors
So gentle pilgrim, here the call
And may Saint Nicholas bless you all.