Killenworth

In the 1890s the children of Charles Pratt, whose Brooklyn oil company became part of John D. Rockefeller's Standard Oil in 1874, began building country houses on family land at Dosoris, in the northern part of Glen Cove. George Dupont Pratt (1869 to 1935) was one of them. His first house there, also called Killenworth, was designed by William B. Tubby around 1897. Like several of his brothers, Pratt later tore down his first house and built a much larger one in its place.

The second Killenworth was designed by the New York architects Trowbridge and Ackerman. The Library of Congress dates their work from 1908 to 1913, and a 2017 local newspaper account says the house was built in early 1913. The Glen Cove Public Library describes it as a Jacobean manor house, and the same newspaper account gives it 49 rooms. The landscape architect James Leal Greenleaf designed the gardens around 1913, within a site and drive plan that the Olmsted Brothers had made for the whole Pratt compound in 1906. Frances Benjamin Johnston photographed the sunken terrace garden, the swimming pool, the tea pavilion and the flower borders in hand-colored glass lantern slides. On June 25, 1918, the estate hosted a garden fete for Italian war relief at which Isadora Duncan's dance troupe performed.

George Pratt died in 1935. After the Second World War the Soviet Union bought the estate as a country retreat for its delegation to the United Nations. The Glen Cove Public Library gives the year as 1946; The Leader, a local paper, gives 1950 and a price of about $75,000. The estate passed to the Russian Federation and is still used by Russia's mission. In the 1980s the Soviet defector Arkady Shevchenko claimed that surveillance equipment had been installed on its top floors.

In late December 2016 the Obama administration ordered two Russian compounds closed, one in Maryland and one on Long Island, in response to Russian interference in the presidential election. Reporters gathered outside Killenworth, but Glen Cove's mayor announced that it would not be closed. The Long Island property that was shut was Norwich House, also known as Elmcroft, in Upper Brookville; its occupants left by noon on December 30, 2016. In February 2022 Nassau County Executive Bruce Blakeman and Representative Lee Zeldin, joined by Ukrainian Americans, called for the diplomats at Killenworth to be expelled. None of the sources consulted for this entry reports that the estate has been closed since.

Killenworth is private diplomatic property and is not open to visitors.