This imposing five-storey fortified house was constructed in 1626 by Sir Jasper Harbert, who left his mark quite literally above the entrance; his coat of arms still adorns the space above the two-centred arch doorway of the entrance tower. The building's defensive nature is evident in its tall chimney stacks and distinctive square-headed windows, complete with transoms and mullions typical of 17th-century Irish architecture.

The castle's design speaks to the uncertain times in which it was built, when comfort and defence went hand in hand. To the south of the main building, visitors can spot the remains of what appears to have been a guardhouse, its gable end still visible. This structure, which ran along an east-west axis, featured a wall walk and formed part of a larger complex of buildings within the protective bawn area; a fortified courtyard that would have sheltered livestock and provided an extra layer of security during raids.

Today, Ballycowan Castle stands as a remarkable example of early 17th-century fortified domestic architecture in Ireland, offering a tangible connection to the plantation period when English and Scottish settlers were establishing themselves across the Irish midlands. Its elevated position and sturdy construction have helped it survive nearly four centuries, though time has inevitably taken its toll on the auxiliary structures that once surrounded the main tower house.