The Earls of Kenmare - descendants of Sir Valentine Browne, who had received Killarney lands during the Tudor plantations - had lived at Kenmare House since 1726. By the 1860s the house was felt to be too modest for the family's status. When Queen Victoria visited Ireland in 1861, she was taken to a hillside above Lough Leane and shown the view. She approved. In 1872 the 4th Earl of Kenmare demolished the old Kenmare House and began work on the new mansion at the elevated site, with views down to the lake. The architect was George Devey, with the work supervised by the Belfast architect W. H. Lynn. According to the architectural critic Jeremy Williams, the result lacked the slowly-accumulated character that Devey's English country houses had. Williams reserved his praise for the westernmost gate lodge - gabled, galleried, and 'Devey at his most delightful'. The lodge survives. The first Killarney House does not.

Lady Kenmare - Gertrude Thynne, granddaughter of the 2nd Marquess of Bath - is said to have driven the project. Her grandfather's seat was Longleat in Wiltshire, the great Elizabethan house, and she wanted Killarney House to evoke it. The result was a red-brick Jacobethan mansion, gabled and oriel-windowed, hung inside with Spanish leather - the kind of expensive nineteenth-century interior that signalled both wealth and a desire to seem older than it actually was. This was not unusual. Across Ireland, descendants of Elizabethan and Jacobean settlers built Jacobethan houses in this period to assert their 'antiquity' against neighbours whose Irish lineages ran much deeper. The first Killarney House burned in 1879, the year after its completion - though the family rebuilt. It burned again, finally, in August 1913. The 5th Earl converted the old Kenmare House stable block for family use and renamed it Kenmare House.

In 1956 Mrs Beatrice Grosvenor - niece of the 7th Earl of Kenmare and granddaughter of the Duke of Westminster - built Knockreer House on the site of the burned Killarney House. Her cousin Francis Pollen designed it. Mrs Grosvenor later donated Knockreer House and its surrounding lands to form Killarney National Park. In the same year, she sold the second Kenmare House together with 25,000 acres to an American syndicate. Three years later that syndicate sold the property to John McShain, an American building contractor - the man who had built the Pentagon and the renovation of the White House under Truman. McShain and his wife Mary Horstmann extensively renovated the building and renamed it Killarney House for a second time. The McShains were not absentee owners. They lived in the house, used it, made it theirs. In 1978 McShain sold most of the estate to the Irish State at a price well below market value, on the understanding that the land would be incorporated into Killarney National Park. He and Mary reserved the house and 52 acres for their lifetimes.

John McShain died in 1989. Mary lived in the house another nine years, until her death in 1998. With both McShains gone, the house and its remaining acres reverted to the Irish State. Then it stood empty. For more than a decade Killarney House was a closed building in a public park - the inside slowly deteriorating, the gardens going their own way without supervision. In July 2011 Leo Varadkar, then Minister for Transport, Tourism and Sport, announced a 7 million euro restoration. After several years of work, Killarney House reopened to the public on 3 April 2016. Visitors now walk through rooms that the Brownes built, the McShains renovated, and the Irish state finally took into permanent public ownership. The Spanish leather is gone. The Elizabethan-Revival mansion is gone. What remains is the third house on the hillside Queen Victoria chose, in a national park created from the lands that an Irish-American contractor sold below market value to keep it intact.