Built by the Roche family who acquired the land from the Condons in the 14th century, this impressive fortification measures 15.5 metres east to west and 9.7 metres north to south. The tower saw renovations during the 18th and 19th centuries, though much of its medieval character remains intact, including what may be the original iron yett (a type of defensive gate) still hanging at the entrance.

The castle’s interior reveals sophisticated defensive features typical of late medieval Irish tower houses. Entry through the pointed-arch doorway on the west wall leads to a vaulted lobby complete with a murder hole overhead, from which defenders could attack unwelcome visitors. A spiral staircase in the southwest corner connects all six floors, each serving different functions; the ground floor housed storage and guard rooms, whilst the upper levels contained living quarters with increasingly comfortable amenities. The second floor features a fireplace with an unusual flat arch of joggled voussoirs, whilst the fourth floor boasts multiple windows with elegant ogee-headed lights and even a bread oven built into the wall chamber.

Throughout the tower, clever defensive elements blend with domestic comforts. Gun loops and murder holes protected vulnerable points, whilst garderobes (medieval toilets) on multiple levels discharged through shafts exiting near the base of the south wall. The wall walk at the top, though now missing its crenellations, once provided views across the surrounding countryside and featured a bartizan (small turret) at the northeast corner. The Roches held Cregg until their lands were forfeited following the 1641-42 rebellion, marking the end of their centuries-long occupation of this remarkable stronghold.