This once-grand structure stood guard at an important crossing point on the River Barrow, where travellers and traders would have passed for generations. When antiquarian Thomas Dineley sketched the castle in 1680, he captured an impressive five-storey building complete with three ornamental gables gracing its front facade and crenellated parapets along its sides. By 1790, another sketch revealed the castle had fallen into ruin, yet remarkably, when photographers arrived eighty years later in 1870, they found it in much the same condition; a testament to the durability of its construction even in abandonment.

The castle’s history is one of destruction and reinvention. The original medieval structure likely underwent substantial rebuilding following Edmund Carew’s siege in 1569, during the turbulent period of English expansion into Ireland. The Gothic-style arches and windows visible in later records probably date from a late eighteenth-century refurbishment, when such romantic architectural elements were fashionable among the landed gentry. When surveyors documented the derelict buildings in 1911, they were recording what remained of centuries of alterations, though much of this collapsed or was demolished by 1931, leaving little of the fifteenth or sixteenth-century original structure intact.

Today, visitors to Clogrenan will find only overgrown foundations and fragments of what appears to be eighteenth-century stonework, including a small portion of an entrance way. In 1806, the castle took on a new role when construction began on Clogrenan House; the old fortress was repurposed as a grand gateway to the estate grounds, its military past giving way to ornamental function. The site has been protected under a preservation order since 1995, ensuring that what little remains of this once-imposing border stronghold will continue to mark this historic river crossing for future generations to discover.