Question: The play on which the 1953 film directed by Joseph L. Mankiewicz was based on was believed to have been written in what year?

Context paragraphs:
Julius Caesar (play): The Tragedy of Julius Caesar is a tragedy by William Shakespeare, believed to have been written in 1599.  It is one of several plays written by Shakespeare based on true events from Roman history, which also include "Coriolanus" and "Antony and Cleopatra".

Julius Caesar (1953 film): Julius Caesar is a 1953 epic Metro-Goldwyn-Mayer film adaptation of the play by Shakespeare, directed by Joseph L. Mankiewicz, who also wrote the uncredited screenplay, and produced by John Houseman.  The original music score is by Miklós Rózsa.  The film stars Marlon Brando as Mark Antony, James Mason as Brutus, John Gielgud as Cassius, Louis Calhern as Julius Caesar, Edmond O'Brien as Casca, Greer Garson as Calpurnia, and Deborah Kerr as Portia.

Million Dollar Legs (1932 film): Million Dollar Legs is a 1932 American Pre-Code comedy film starring Jack Oakie and W. C. Fields, directed by Edward F. Cline, produced by Herman J. Mankiewicz (co-writer of "Citizen Kane") and B. P. Schulberg, co-written by Joseph L. Mankiewicz, and released by Paramount Pictures.  The film was inspired by the 1932 Summer Olympics, held in Los Angeles.

The Dummy (1929 film): The Dummy is a 1929 American comedy film directed by Robert Milton and written by Harriet Ford, Harvey J. O'Higgins, Herman J. Mankiewicz and Joseph L. Mankiewicz.  The film stars Fredric March, John Cromwell, Fred Kohler, Mickey Bennett, Vondell Darr, Jack Oakie and ZaSu Pitts.  The film was released on March 9, 1929, by Paramount Pictures.

Cleopatra (1963 film): Cleopatra is a 1963 American epic historical drama film chronicling the struggles of Cleopatra VII, the young Queen of Egypt, to resist the imperial ambitions of Rome.  It was directed by Joseph L. Mankiewicz and shot in the 70 mm Todd-AO format, with a screenplay adapted by Mankiewicz, Ranald MacDougall and Sidney Buchman from a book by Carlo Maria Franzero.  The film stars Elizabeth Taylor, Richard Burton, Rex Harrison, Roddy McDowall, and Martin Landau.

There Was a Crooked Man...: There Was a Crooked Man... is a 1970 western starring Kirk Douglas and Henry Fonda and directed by Joseph L. Mankiewicz.  This was the only western made by Mankiewicz, director of such notable films as "All About Eve", "Guys and Dolls" and "Cleopatra".  It was written by David Newman and Robert Benton, their first script after "Bonnie and Clyde".

People Will Talk: People Will Talk is a 1951 romantic comedy/drama film directed by Joseph L. Mankiewicz and produced by Darryl F. Zanuck from a screenplay by Mankiewicz, based on the German play by Curt Goetz, which had been made into a movie in Germany ("Doctor Praetorius", 1950).  Released by Twentieth Century Fox, the film stars Cary Grant and Jeanne Crain, with supporting performances by Hume Cronyn, Finlay Currie, Walter Slezak, and Sidney Blackmer.

River of Romance: River of Romance is a 1929 American drama film directed by Richard Wallace and written by Ethel Doherty, Joseph L. Mankiewicz, Dan Totheroh and John V.A. Weaver.  The film stars Charles 'Buddy' Rogers, Mary Brian, June Collyer, Henry B. Walthall, Wallace Beery, Fred Kohler and Natalie Kingston.  It is based on the play "Magnolia" by Booth Tarkington.  The film was released on June 29, 1929, by Paramount Pictures.

Sleuth (1972 film): Sleuth is a 1972 British mystery thriller film directed by Joseph L. Mankiewicz and starring Laurence Olivier and Michael Caine.  The screenplay by playwright Anthony Shaffer was based on his 1970 Tony Award-winning play.  Both Olivier and Caine were nominated for Academy Awards for their performances.  This was Mankiewicz's final film.  Critics gave the film overwhelmingly positive reviews, and would later note similarities between it and Caine's 1982 film "Deathtrap".

Dragonwyck (film): Dragonwyck is a 1946 American period drama film made by Twentieth Century-Fox.  It was directed by Joseph L. Mankiewicz and produced by Darryl F. Zanuck and Ernst Lubitsch (uncredited) from a screenplay by Mankiewicz, based on the novel "Dragonwyck" by Anya Seton.  The music score was by Alfred Newman and the cinematography by Arthur C. Miller.  The film stars Gene Tierney, Walter Huston and Vincent Price.

Supporting paragraphs: Julius Caesar (1953 film) Julius Caesar (play)
Answer: 1599