Built around 1450 by the O’Reilly clan, this castle commanded views across the surrounding landscape and served as a symbol of power in what would become a contested borderland. By the late 16th century, it had grown into the most important fortification in Tullygarvey barony, a testament to the O’Reillys’ enduring influence in the region during turbulent times.

The castle’s story took a dramatic turn following the Plantation of Ulster in the early 17th century, when English and Scottish settlers were granted lands previously held by Gaelic families. The fortress passed into the hands of the Moore family, becoming the administrative heart of their new manor. This transition marked a profound shift in the area’s social and political landscape; what had been a Gaelic stronghold became a centre of colonial administration.

Today, nothing remains visible above ground at Tullyvin to hint at this once-formidable structure. The hillock that once supported thick stone walls and defensive towers now stands empty, its strategic importance long forgotten. Archaeological records from the mid-20th century confirm the site’s location, but time and likely stone robbing for later building projects have erased all physical traces of both the O’Reilly castle and the Moore manor house that succeeded it.