Ardnabannon House, located near Castlewellan in County Down, was designed by architect Thomas Turner for Charles Murland (1820–1887), the youngest son of James Murland—an influential figure who oversaw the expansion of the Murland family’s business empire during the 19th century. In 1967, the property was acquired by the Down County Education Committee and repurposed as an Outdoor Pursuits Centre. While today it welcomes school groups and youth organisations, some say that not everyone who walks its halls is alive.

According to local legend, the haunting of Ardnabannon originates not from the current house, but from the manor that once stood on the same grounds. That earlier residence was owned by a wealthy local family, who had a single heir—a son expected to inherit the estate. However, scandal struck when the young man fell in love with a nun from a nearby convent. Fearing disgrace, the family took matters into their own hands. One bitter winter, they allegedly kidnapped the nun, bound her in chains, and left her tied up on the snow-covered grounds of the estate. Exposed to the freezing elements, she died of hypothermia. Her body was found blue with cold—giving rise to the ghostly name that endures today: The Blue Nun.

It is said that her restless spirit still haunts the west corridor of Ardnabannon House, forever searching for the man she loved. Witnesses have reported hearing the sound of chains clinking in the dead of night—believed to be the same chains used to bind her. Over the years, many schoolchildren visiting the centre have claimed to see her ghost wandering the halls during their stay.

Whether cautionary tale or genuine haunting, the story of the Blue Nun remains one of County Down’s most enduring and chilling legends.