It’s something of a miracle that any film ever manages to get made. It takes so many people and so many resources to put together a production worth filming that it sometimes seems impossible to undertake even the simplest of intimate dramas, let alone an ambitious big-budget epic.

From the perspective of an audience member, it’s easy to forget about the production woes that plague so many films from conception to completion, so let’s look at some of the biggest missed opportunities in film history. These are the movies that sound amazing due to the source material and talent involved that, for one reason or another, never made it to the big screen.

Stanley Kubrick’s ‘Napoleon’

Stanley Kubrick was known for his enormous ambition and attention to details — traits that played a part in sabotaging his long-in-the-pipeline production of Napoleon, an historical epic tracking the life of the great French conqueror.

The film, originally planned as his follow-up to 1968’s 2001: A Space Odyssey, would require a $5 million production budget and more than 30,000 extras for battle sequences. David Hemmings was cast in the lead and Audrey Hepburn as Josephine. Kubrick worked tirelessly to acquire every bit of information he could about Napoleon’s life and career, but by the time he was satisfied with his sprawling vision, the studios were too timid to commit, since historical epics had gone out of vogue and the similarly focused film Waterloo flopped upon release.

Today, the 147-page script is available to read online and Steven Spielberg is working to develop the project as a miniseries.

Alejandro Jodorowsky’s ‘Dune’

The failed film notorious enough to inspire a whole documentary about the canceled project, Dune was to be surrealist director Alejandro Jodorowsky’s adaptation of Frank Herbert’s epic classic of science fiction literature. During the ‘70s, the counterculture filmmaker worked to assemble some of the greatest creative minds of the time, including H.R. Giger, Pink Floyd, Salvador Dali, Mick Jagger, Orson Welles, Gloria Swanson and visual effects supervisor Dave O’Bannon.

It would be almost impossible for anything to live up to the potential suggested by this source material and the creative team involved. Financiers cancelled the project before it could get far, based in part on the suggestion that the finished film could run as long as ten hours and the novel eventually made it to the big screen, courtesy of another beloved surrealist filmmaker, David Lynch.

Harold Ramis’s ‘A Confederacy of Dunces’

John Kennedy Toole’s A Confederacy of Dunces is one of the great comic novels of the 20^th century for its colorful depiction of various incompetent New Orleans denizens, led by the obese smart-talking doofus Ignatius Reilly, and for a long time, it seemed as though Harold Ramis (Stripes, Ghostbusters, Groundhog Day) would be the one to adapt the novel to film.

John Belushi and Richard Pryor were signed on to star (both of whom would have been perfect), but Belushi’s early demise in ’82 threw things into disarray. Names like John Candy, Chris Farley, John Goodman, Jack Black and Zach Galifianakis have all been thrown around in the coming decades, and directorial duties for the planned project went from Ramis first to Steven Soderbergh (Ocean’s Eleven, Traffic) and then to David Gordon Green (Pineapple Express, Joe).

If the shifting production plans and legal troubles ever let up, we may get to see some version of A Confederacy of Dunces onscreen, probably in another three decades or so.

Louis Malle’s ‘Moon Over Miami’

More than three decades before David O. Russell used the ABSCAM scandal as the inspiration for his film American Hustle, French director Louis Malle was all set to adapt the same story into a film starring Dan Akroyd and John Belushi in the roles later played by Bradley Cooper and Christian Bale, respectively.

With Malle given the greenlight based on the success of his last film, Atlantic City, the former Blues Brothers were set to legitimize themselves as serious actors. Akroyd loved the script, but Belushi never had the chance to read it before his death in 1982.

David Cronenberg’s ‘Frankenstein’

Canadian film producer approached Canadian director David Cronenberg in the ‘80s about adapting Mary Shelley’s classic horror novel Frankenstein for the big screen once more. Cronenberg dispassionately expressed interest, and somehow word got to the press, who touted the production as a sure thing when, as far as anyone knows, nothing ever got off the ground concerning the project.

“It would be a more rethinking than a remake. For one thing I’d try to retain Shelley’s original concept of the creature being an intelligent, sensitive man. Not just a beast,” Cronenberg said about his plans for the project. Cronenberg, whose earlier films represent the best and most nauseating the horror genre has to offer, would have been a natural fit for the classic tale of man playing God, but it was not to be.

Clair Noto’s ‘The Tourist’

Often a script becomes well-known throughout Hollywood circles but simply can’t find the right hands to realize the story. Clair Noto’s science fiction screenplay The Tourist is a prime example, touted as a Blade Runner-esque sci-fi noir about a community of aliens living covertly in Manhattan who meet to have sex and plot ways to return to their home planets.

Noto began the script in 1980 but languished for so long that eventually other films made use of The Tourist’s ideas, most notably Men in Black, which is like a comedic The Tourist stripped of its sexual overtones with a human buddy cop duo inserted as leads.

H.R. Giger (of Alien fame) created a series of alien designs to accompany the film, but the script and the designs proved far too discomforting for studio execs reluctant to greenlight a project that leaned so heavily on dark themes like corruption, xenophobia and sexual agony. Noto was eventually booted from her own deeply personal project, and studios tried to commercialize the idea for decades to no avail.

Paul Verhoeven’s ‘Crusade’

At his best, Paul Verhoeven makes popcorn movies that conceal a clever, cynical approach to modern life and media — movies like Robocop and Starship Troopers that entertain while satirizing themselves.

Crusade was to be Verhoeven’s second collaboration with Total Recall star Arnold Schwarzenegger (then the biggest star in the world). An historical epic focused on the papal corruption that spawned the First Crusade, Verhoeven used this bloody era in human history to satirize modern anti-Arab prejudices and, knowing him, a whole host of other controversial topics.

Other talent attached included John Turturro, Robert Duvall and Jennifer Connolly. In the end, the studio backed out of the project due to fear of backlash from conservative Christians and hesitation to give Verhoeven the budget he required to make such a film. Co-writer Gary Goldman put it this way: “[Paul] doesn’t really lie about budgeting, which is a mistake because there’s no way to get these movies made without lying.”

Sergio Leone’s ‘Leningrad: The 900 Days’

Imagine the epic scope and tactile imagery of The Good, the Bad and the Ugly brought to one of the Russian front of World War 2’s bloodiest battles. Director Sergio Leone was set to make just such a film, based on Harris Salisbury’s non-fiction work The 900 Days: The Siege of Leningrad and potentially starring Robert De Niro as an American photographer trapped in the city during the siege who falls in love with a Russian woman before dying on liberation day.

The script was never finished, but Leone had an outline of the story and ambitious plans for a first shot that would have swept across the activity of the entire city before settling upon an invading German Panzer division moving in to begin the attack. He managed to secure $100 million in financing by 1989 but died just two days before signing the final deal at the age of 60.