The Godfather Part II was the first sequel ever to win Best Picture
Francis Ford Coppola refused to simply remake his hit. His 1974 follow-up runs two stories side by side: young Vito Corleone rising in immigrant New York, and his son Michael hollowing out the family decades later. It collected six Oscars, including Best Picture, a first for any sequel.
Coppola's idea was to set a father and a son against each other at the same stage of life, both in their thirties, one building a family and the other destroying it. Robert De Niro plays Vito, who flees Sicily at nine in 1901 after a mafia boss murders his relatives and is renamed Corleone by an immigration officer. Al Pacino plays Michael in 1958, running the business from Lake Tahoe and surviving an attempt on his life.
Mario Puzo began a sequel script in December 1971, before the first film had even opened, under the grim working title The Death of Michael Corleone. Production nearly collapsed when Pacino's lawyers said he disliked the script; Coppola rewrote it overnight and won him back. Marlon Brando agreed to appear in a birthday flashback, then failed to show up, so the scene was rewritten the same day. Coppola said the Senate hearing scenes drew on the real Valachi hearings.
Filming ran from October 1, 1973 to June 19, 1974. Cuban scenes were staged in Santo Domingo in the Dominican Republic, and the Sicilian town seen on screen is Forza d'Agrò. The planned $6 million budget climbed past $11 million. Box-office takings reached $48 million in North America and as much as $93 million globally, earning eleven Oscar nominations and wins for Coppola as director and De Niro as supporting actor.
Pauline Kael argued the two films form a single work in two parts, with the sequel making the first film's themes explicit. The American Film Institute placed it 32nd among American films in 1997 and again a decade later, and the Library of Congress chose it for the National Film Registry in 1993. The trilogy ended with The Godfather Part III in 1990.
Source: The Godfather Part II