The Giant’s Ring

Set into the stone wall that surrounds the Giant's Ring is an engraved stone plaque that reads:

THIS WALL FOR THE PROTECTION OF

THE GIANT'S RING

WAS ERECTED A.D. MDCCCXLI BY

ARTHUR VISCOUNT DUNGANNON

[On whose] estate this singular relique of

is situated and who earnestly

recommends it to the care of his successors.

The bits in square brackets are illegible, so I've guessed the probable wording.