Hellfire Club, Montpelier Hill

Atop Montpelier Hill in the Dublin Mountains stand the ruins of a hunting lodge built in 1725 for William 'Speaker' Conolly, one of the wealthiest and most powerful men in 18th-century Ireland. The site already carried an ominous reputation: it had been the location of an ancient passage tomb and cairn, which Conolly's builders demolished, reportedly using one of the tomb's standing stones as the lintel for the lodge's main fireplace — an act of desecration locals blamed for a run of bad luck that followed, including the lodge's roof being torn off by storms not long after completion.

After Conolly's death the lodge passed into the hands of the Irish Hellfire Club, founded around 1735 by figures including Richard Parsons, a group notorious among Dublin's aristocracy for hard drinking, gambling, and rumoured devil-worship and black magic. The building's grim, blackened appearance and the club's scandalous reputation fused into the site's most famous legend: that during a card game, a player dropped a card, and on bending to retrieve it saw that a stranger seated at the table had a cloven hoof instead of a foot. The 'stranger' — the Devil himself — vanished in a burst of flame, leaving the lodge gutted by fire.

Today the ruined lodge is one of Ireland's most visited 'haunted' sites, with visitors reporting strange smells, sounds, and a heavy atmosphere inside its roofless rooms — a reputation built on three centuries of layered history, from desecrated tomb to aristocratic den of vice to supernatural landmark.