Known as the ‘Giant’s Grave’ on Ordnance Survey maps from 1833 and 1846-8, this site consisted of two upright stones standing approximately 9 metres apart, each reaching about 1.2 metres in height. The dual naming of the site reveals something of its enigmatic nature; whilst consistently labelled as ‘Giant’s Grave’ on published maps, pre-publication surveys referred to it as ‘Standing Stones’, suggesting uncertainty about its true purpose even amongst contemporary observers.

Thomas Fagan’s 1846 examination of the site provides our most detailed account, though his investigation was hampered by growing grain crops that obscured much of the ground surface. By the time the 1905 Ordnance Survey maps were produced, the stones had vanished entirely, with the location marked merely as ‘Giant’s Grave (Site of)’, indicating that whatever remained of this ancient monument had been removed, likely repurposed as building material or cleared for agricultural purposes. This disappearance between 1846 and 1905 reflects a broader pattern of megalithic destruction across Ireland during the period of agricultural intensification.

Despite its evocative name, which follows a common Irish tradition of attributing ancient monuments to giants or mythical figures, modern archaeological assessment suggests these stones were unlikely to have been part of a megalithic tomb. The spacing and configuration don’t match typical tomb architecture found elsewhere in Donegal, leaving the true nature of this lost monument open to speculation. Whether it served as a territorial marker, held ritual significance, or fulfilled some other purpose in the prehistoric landscape of north Donegal, the Giant’s Grave of Portlough remains one of many archaeological puzzles lost to time and agricultural progress.