This building – an occasional summer residence built in around 1725 by William Conolly – was originally called Mount Pelier and since its construction the hill has also gone by the same name.

[7] Montpelier is the closest to Dublin city of the group of mountains – along with Killakee, Featherbed Bog, Kippure, Seefingan, Corrig, Seahan, Ballymorefinn, Carrigeenoura, and Slievenabawnogue – that form the ridge that bounds the Glenasmole valley.

Members of the Irish Hell Fire Club, which was active in the years 1735 to 1741, used Mount Pelier summer residence as a meeting place.

White's son, Samuel, oversaw the development of extensive formal gardens on the estate, including the construction of several glasshouses by Richard Turner.

The building now known as the Hell Fire Club was built around 1725 as a hunting lodge by William Conolly, the Speaker of the Irish House of Commons.

[14] The identity of the architect is unknown: the author Michael Fewer has suggested it may have been Edward Lovett Pearce (1699–1733) who was employed by Conolly to carry out works at Castletown in 1724.

[26] Accounts of the club's meetings claim that members drank "scaltheen", a mixture of whiskey and hot butter, and that they left a chair vacant at each gathering for the Devil.

[33] One tale centres on club member Simon Luttrell, Lord Irnham, later Earl of Carhampton, one time Sheriff of Dublin.

[40] Joseph Holt, a general of the Society of the United Irishmen recorded in his memoirs that he spent a night in the ruin of Montpelier while on the run following the 1798 Rebellion.

I felt confident of the protection of the Almighty that the name of enchantment and the idle stories that were told of the place had but a slight hold of my mind.

[42] Today, the building is maintained by Coillte, who manage the forestry plantations on Montpelier's slopes, and have installed concrete stairs and iron safety rails across the upper windows.

"[44] It appears from this description that the central chamber of the monument – which was a passage grave[19] – survived intact even after Mount Pelier was constructed.

[53] One night, a friend of the O'Briens, artist Tom McAssey, and two workmen were confronted by a spectral figure and a black cat with glowing red eyes.

[56] In 1971, a plumber working in the house discovered a grave with a skeleton of a small figure, most likely that of a child or, perhaps, the body of the dwarf alleged to have been sacrificed by the members of the Hell Fire Club.

[42] The Luttrell family held onto the estate until the seventeenth century when it was relinquished to Dudley Loftus and then passed to William Conolly.

[62] Niven laid out two Victorian formal gardens of gravel walks, terraces and exotic trees decorated with statues of Greek and Roman gods.

[62] A second walled garden in a vale in the woods below the house contained more fountains and a range of glasshouses designed by Richard Turner.

"[63] When Samuel White's widow, Anne, died in 1880, she bequeathed the estate to her late husband's nephew, John Thomas, 6th Baron Massy.

[64] The Massys were a Protestant Ascendancy family who had come to Ireland in 1641 and owned extensive lands in Counties Limerick, Leitrim and Tipperary.

[68] However, as a result of declining rental income and poor investment decisions, John Thomas Massy was in considerable debt when he died in 1915.

[69] The Massys initially moved into the Stewards House before taking up residence in Beehive Cottage, the estate's gate lodge, by agreement with the bank.

[9] The trees have reclaimed most of the land once occupied by the formal gardens: all that remains is the brickwork at the rear of the Turner glasshouses and the system of irrigation canals and ponds for the exotic plants contained within.

[32] The building was originally two storeys high with bow windows each side of the hall door, above which was the Ely coat of arms.

[79] At each side of the house was an arched gate from which extended a range of ancillary buildings, terminating in a three-storeyed tower with an embattled top and pointed windows.

[81] The Elys subsequently abandoned the residence and the building soon fell into ruin, mainly at the hands of a tenant called Jack Kelly who wrecked the house to ensure his tenancy would not be disturbed.

[83] In the land adjacent to Carthy's Castle is Orlagh House which has been owned by the Augustinian Order since the mid-nineteenth century and is a retreat and conference centre run by the friars.

[84] He was also a magistrate and was instrumental in condemning three members of the Kearney family to death for the murder of John Kinlan, the gamekeeper at Friarstown, near Bohernabreena, in 1816.

[58] Lord Massy's Estate and Montpelier are also traversed by the Dublin Mountains Way hiking trail that runs between Shankill and Tallaght.

Local residents and community groups have expressed opposition to the plan, citing the delicate ecosystem of the area, risks of damage to recently discovered megalithic artwork, and fears of traffic congestion resulting from a possible 300,000 visitors to the site.

[90] These groups have launched a campaign entitled "Save the Hellfire" aimed at persuading An Bord Pleanála to refuse planning permission for the project.