Most people who make the climb know it as the Hellfire Club, a name that conjures lurid Georgian folklore far more readily than the architectural reality: a derelict, vaulted stone hunting lodge, open to the sky in places, sitting squat and exposed on a hill summit with panoramic views stretching north and east across the city and the bay beyond.

The building was originally commissioned around 1729 by William Connolly, the Right Honourable Speaker of the Irish House of Commons and one of the wealthiest men in Ireland at the time. It was constructed at the centre of an extensive deerpark, intended as a hunting lodge rather than a residence, and the structure reflects that practical purpose. The lodge is a five-bay, single-storey-over-basement building, meaning the main living rooms sat above a lower ground floor that housed the kitchen, servants' quarters, and the staircase connecting them. According to researcher Healy, the upper floor contained two large rooms, a hall, and a small loft above the parlour. A flight of stone steps led up to the hall door. The building was burnt soon after construction, and the roof was subsequently repaired using a vaulted stone construction, which gives the interior its distinctive heavy, cavernous character. Two wings extend from the main block, each with small rooms and sloping stone roofs, and a rear wing features a small semi-circular window. Inside, fireplaces, arched doorways, and niches survive, connected by a gallery.

The hill is accessible from the Massey Woods car park off the Killakee Road, within the Dublin Mountains, and the walk to the summit takes roughly thirty to forty minutes on a marked forest trail. The forestry that now surrounds the site restricts the views to the south and west, so the most rewarding aspect remains the northward and eastward panorama. The ruin itself is unfenced and freely accessible, though the interior stonework and uneven floors require some care underfoot. In poor weather the exposed summit can be considerably colder and windier than the car park below, which is worth keeping in mind before setting out.