13 Winston Churchill ashore from a cruise aboard Aristotle Onassis’s yacht Christina, with Yugoslav premier Marshall Tito, September 1960 Credit: Alamy 13 ...

Aristotle Onassis had a longtime affair with opera singer Maria Callas that lasted until his death in 1975 at age 69. Callas is the subject of a biopic starring Angelina Jolie.

Callas and Meneghini (pictured above) joined Onassis aboard his famous yacht, the “Christina O.” Callas and Onassis's affair reportedly began on the boat.

Callas and Meneghini (pictured above) joined Onassis aboard his famous yacht, the “Christina O.” Callas and Onassis's affair reportedly began on the boat.

Keystone - Getty Images Callas and Meneghini (pictured above) joined Onassis aboard his famous yacht, the “Christina O.” Callas and Onassis's affair reportedly began on the boat.

Keystone - Getty Images Callas and Meneghini (pictured above) joined Onassis aboard his famous yacht, the “Christina O.” Callas and Onassis's affair reportedly began on the boat. Athina “Tina” Onassis ...

Aristotle Onassis and Maria Callas 'couldn't live without the other one,' his longtime personal secretary Kiki Feroudi Moutsatsos tells PEOPLE. And Onassis' wife, Jackie Kennedy, knew about the ...

Aristotle Onassis hosts Jackie Kennedy (whose husband US president John F. Kennedy stayed behind in Washington DC) and Franklin Roosevelt Jr as they cruise the Mediterranean aboard his yacht ...

The dress is being offered up by a private couple that befriended Onassis and Onassis Kennedy on the private yacht, Christina O, name after Onassis’ daughter. Jackie O’s Valentino wedding dress to ...

Originally built as an anti-submarine frigate for the Royal Canadian Navy, Christina O was bought for scrap value by shipping magnate Aristotle Onassis in 1954.