The Soviet Union bought the three-story, 49-room Killenworth mansion in Glen Cove in 1946, according to a Newsday story from that year. Killenworth, on Dosoris Lane near the Glen Cove YMCA and Glen Cove High School, was built in 1912 for industrialist George Dupont Pratt. The 26,459-square-foot stone house sits on 36 acres. The property is worth $17,148,400, according to Nassau County assessment records. It has a pool, a greenhouse and a tennis court, according to county records.

Credit: Orin Finkle

The front facade of the Killenworth estate in Glen Cove is seen in 1925.

Credit: Orin Finkle

The living room of the Killenworth estate in Glen Cove is seen in 1925. The 26,459-square-foot house was built in 1912 by philanthropist and Standard Oil heir George Dupont Pratt.

Credit: Orin Finkle

The entrance hall of the Killenworth estate in Glen Cove in 1950. The Soviets installed electronic surveillance equipment at Killenworth to spy on the Long Island defense industry and high-tech firms, a Soviet defector and a U.S. official told Newsday in 1982.

Credit: Orin Finkle

An aerial view of the Killenworth estate in Glen Cove in 1950. The Soviets also once hosted Fidel Castro at the mansion, McClatchy reported.

Credit: Orin Finkle

The rear facade of the Killenworth estate in Glen Cove is seen in 1950.

Credit: Orin Finkle

The Killenworth estate in Glen Cove is seen in 1985. Reginald Spinello, the current Glen Cove mayor, recalled that when he was a child in 1960 during a time of tense relations between the Soviet Union and the United States, Soviet leader Nikita Khrushchev visited the estate.

Credit: Orin Finkle

The Killenworth estate in Glen Cove is seen in 1985.

Credit: Orin Finkle

The Killenworth estate in Glen Cove is seen in 1985.

Credit: Newsday / Cliff De Bear

The Killenworth mansion in Glen Cove is seen on May 20, 1965.

Credit: Newsday / Jim Nightingale

Soviet leader Nikita S. Khrushchev visited the Killenworth estate in Glen Cove in 1960.

Credit: Newsday / Chris Hatch

A vaulted archway at the Killenworth estate in Glen Cove, seen on May 18, 1984.

Credit: Newsday / Chris Hatch

The large sitting room at the Killenworth estate in Glen Cove, seen on May 18, 1984.

Credit: Newsday / Karen Wiles Stabile

The swimming pool at the Killenworth estate in Glen Cove, seen on July 3, 1992.

Credit: Newsday / Karen Wiles Stabile

A staircase at the Killenworth estate in Glen Cove, seen on July 3, 1992.

Credit: Newsday / Karen Wiles Stabile

Leonid Balakin Orenberg, a guard at Killenworth, stands at the entrance of the estate in Glen Cove on July 3, 1992.

Credit: Newsday

The Killenworth estate in Glen Cove is seen in an undated photo.

Credit: Newsday / Bill Davis

In an undated photo, Evgeny Deineko of the Russian Federation to the UN points to a French tapestry inside the Killenworth mansion in Glen Cove.

Credit: Newsday / Bill Davis

Scene from an open house and tour of Killenworth, the Russian compound in Glen Cove.

Credit: Newsday / Bill Davis

The living room of the Killenworth estate in Glen Cove is seen in an undated photo.

Credit: Newsday / Bill Davis

The conservatory at the Killenworth estate in Glen Cove is seen in an undated photo.

Bethpage FCU changes name ... Smithtown WWII vet turns 100 ... What's up on LI Credit: Newsday

Gaetz withdraws as Trump's AG pick ... Sands Meadowbrook proposal ... Bethpage FCU changes name ... Cost of Bethpage cleanup