The motte, which measures between 28 and 36 metres at its base and rises to heights of 3.4 to 5.6 metres, retains its impressive form from the southwest to northeast sections, though quarrying and agricultural activities have altered other portions over the centuries. The eastern bailey, roughly 65 metres east to west and 55 metres north to south, complements the mound, whilst the natural ridge to the north has been deliberately scarped to enhance the site’s defensive capabilities.

The site gained considerable archaeological attention during nineteenth-century excavations led by Lefroy in 1871, which, whilst damaging the southern side of the motte, yielded remarkable finds including a bronze axe and a particularly intriguing bronze sword plate. This sword plate bore a runic inscription that translates to ‘Domnal Seals-head owned this sword’, offering a rare glimpse into the personal possessions and naming customs of the site’s medieval inhabitants. These excavations also revealed a souterrain beneath the motte, adding another layer to our understanding of the site’s complexity and use over time.

Today, visitors can still appreciate the substantial earthworks despite modern intrusions; a field fence and laneway have partially compromised the eastern and southern bailey escarpments. Within the southwest portion of the bailey, a rectangular enclosure defined by low earthen banks (measuring 11 metres east to west and 3.5 metres north to south) likely represents a later addition to the site. Protected as National Monument No. 144, Greenmount stands as a testament to Ireland’s layered history, where Viking-age runic inscriptions meet Norman defensive architecture on a Louth hilltop that has witnessed centuries of change.