Anthony thinks he may know where all the stone from here may have ended up.
http://mythicalireland.com/ancientsites/stonehenge/irelandstonehenge.html
Ballynahatne
and now let's think of a big bank with stones inside it -
hhmmmm .... I know it's not near Dundalk as such, but these early antiquarian-type visitors to these to shores often got places mixed up.
Now it could be that two huge banked enclosures happend to be in townlands called something like Ballynahatty. Quite unlikely - or is it? Anyone know what Ballynahatty translates to? Is it town of the bloody big bank?
Here's a radical suggestion:
The passage tomb in the centre of the Giant's Ring is a folly built from the last few remaining stones from the original mouments within the bank.
[just for the record - I haven't checked any dates, excavations or whether there are any drawings of the Giant's Ring that are contemporary with the plan of "Ireland's Stonehenge".]