The site takes its name from a mythological queen, Odhbha, whose burial mound here served as a significant landmark long before the Normans arrived. According to legend, she was the estranged wife of Éremón, a leader of the mythical Milesian invasion, who followed him from Spain to Ireland with her own sons. Such was the mound’s importance that it became the setting for major battles in 607, 890, 1016, and 1072.

Following the Norman conquest, Hugh de Lacy granted the barony of Navan and Ardbraccan to Jocelin de Angelo around 1175, according to the ‘Song of Dermot and the Earl’. De Angelo, whose name would eventually morph into Nangle, cleverly adapted Queen Odhbha’s ancient burial mound into a motte and bailey castle, making it the administrative centre of his new territory. The motte itself is an impressive structure; a flat-topped earthen mound measuring 15 metres across at its summit and 37 metres at its base, rising between 4.5 and 6.8 metres high depending on which side you approach from. A small crescent-shaped bailey extends from the northwest side, defined by a steep four-metre scarp, whilst remnants of a defensive fosse can still be traced around the northern perimeter.

Archaeological investigations have revealed glimpses of the site’s long occupation. Testing in 1997 uncovered two disturbed burials about 70 metres northwest of the motte; a young man aged 18 to 23 and a woman aged 31 to 45. More recent work in 2021, including geophysical surveys and excavation just 20 metres north of the motte, identified several ditches, whilst metal detection turned up what might be an iron strap-end. Though quarrying in the 19th century damaged the southern and eastern approaches, and housing development has since filled the old quarry, the motte remains a striking reminder of how successive cultures have shaped and reshaped this commanding hilltop position.