The structure, built from roughly coursed limestone rubble, retains only portions of its north and west walls, with an 18th-century house later grafted onto its northern side. Just to the southeast sits a medieval church, creating an intriguing settlement pattern that mirrors similar sites like Garrycastle, where medieval and later Georgian architecture coexist in surprising harmony.

The tower house itself is nearly square, measuring about 10.4 metres north to south and 9.9 metres east to west, with walls nearly two metres thick that show a slight outward slope at the base for added stability. Originally rising two storeys, the structure likely had its main entrance in the now-ruined east wall. A rebuilt doorway in the north wall’s western end reveals the tower’s defensive sophistication; from here, a mural staircase wound upwards through the walls, granting access to the first floor whilst a passage led to what appears to have been a guard room. The northwest corner housed defensive chambers on both levels, with a musket loop on the first floor positioned directly above the ground floor guard room, and evidence suggests a wall walk once crowned the structure.

The tower house sits within a largely intact bawn wall that runs south from the southwest corner before turning east, enclosing a courtyard where traces of cobblestone paving survive in the southwest corner. Several outhouses have been built against this defensive wall over the centuries, showing how the site evolved from a fortified residence to a more domestic complex. This layering of medieval fortification, Georgian domestic architecture, and agricultural buildings creates a remarkably complete picture of how Irish rural settlements developed and adapted through the centuries, making Eglish Castle a compelling example of Ireland’s architectural evolution.