1. Mozart’s Requiem

Shortly before his death in 1791, the famed composer Wolfgang Amadeus Mozart was contacted by a mysterious stranger and commissioned to write a Requiem to be played at a ceremony for the man’s deceased wife. Mozart, who was ailing from an unidentified illness, supposedly took the task as a sign of his own impending mortality, and even came to believe that the piece he was composing was actually a requiem for his own funeral. Mozart died before the piece could be completed, and the missing movements were finished by one of his students, Franz Sussmayr. The piece was then given to the mysterious patron, who turned out to be Franz Von Walsegg, an eccentric count who was known for secretly commissioning works of music and then passing them off as his own compositions. Mozart’s wife Constanze eventually identified the piece as belonging to her husband, but beyond this the story is filled with rumors and half truths, and to this day it is not known for certain which parts of the Requiem were altered or added on later, or just why the famed composer became so paranoid and fearful in his final days.

2. Da Vinci’s Gran Cavallo

Since he was known to quickly lose interest and move onto other projects, Leonardo Da Vinci is said to have left behind quite a few unfinished works of art. His most famous unfinished masterpiece, however, was left incomplete due to circumstances outside his control. In the fifteenth century, Da Vinci was commissioned by the Duke Of Milan to build a statue of a horse to honor his father. Da Vinci spent twelve years working on the statue, and in 1492 he unveiled the 23-foot tall clay model of his “Gran Cavallo,” which was praised by many as one of the most beautiful works of art ever created. But before the mold of the horse could be cast in bronze, war broke out between France and Italy. The Duke then decided to donate the 200,000 pounds of metal intended for the horse to the military, which used it to build cannons. Da Vinci’s massive horse statue was never completed, and it is said that the invading French archers later used his clay horse model for target practice.

3. Gaudi’s Sagrada Familia

Perhaps the longest running architectural project in recent memory, the Sagrada Familia is a massive and uniquely designed Roman Catholic cathedral in Barcelona that has been under construction since 1882. The building was designed by famed architect Antoni Gaudi, and was considered to be his crowning achievement. Gaudi worked on the church for forty years, and even devoted his last fifteen years exclusively to it, but he died in 1926 before it was completed. The project was then taken over by Gaudi’s assistants, who continued work on it even after it was badly damaged by anarchists during the Spanish Civil War. Since then, the project has been in a constant state of flux, with a number of different architects and builders coming on to it, but it has yet to be opened or actively used as a church. Even in its unfinished state, the Sagrada Familia is Barcelona’s most famous tourist attraction, and authorities have claimed that the building may finally be open to the public by 2010.

4. Stuart’s Portrait of George Washington

The painting of George Washington that is found on the modern one-dollar bill was done by Gilbert Stuart, a renowned painter who drew portraits of a number of kings and presidents. What is not well known is that the dollar bill painting of Washington was never completed. The painting, known as The Athenaeum, was intentionally left incomplete by Stuart so that he could hold onto it and easily draw copies, which he then sold for $100 a piece. Stuart is said to have painted as many as seventy reproductions of The Athenaeum, but he never finished the original before his death in 1828. For his part, Washington is said to have been particularly annoyed by Stuart’s behavior, and once even traveled to the artist’s studio and demanded to be given his portrait.

5. Orson Welles’ The Other Side of the Wind

Orson Welles is regarded by many as one of the world’s greatest filmmakers, and his debut Citizen Kane is widely considered to be the best film ever made. Welles’ career was fraught with a number of forgotten and abandoned projects, and at the time of his death in 1985 he was in the middle of work on two films. The most of famous of these was The Other Side of the Wind, a film starring Dennis Hopper and John Huston that Welles had been working on since the late sixties. The movie was nearly complete in 1979, but Welles ran into huge financial and legal complications that halted production. The biggest of these was that the film’s major financial backer, the brother-in-law of the Shah of Iran, pulled funding after the Shah was overthrown and exiled from the country. This led to a years-long controversy over ownership of The Other Side of the Wind, and the film was never finished. In the years since Welles’ death, there have been a number of attempts to edit and release the film, and recent rumors suggest that a version of it may debut in 2010.

6. Coleridge’s Kubla Khan

One of the most famous opening lines in poetry begins “In Xanadu did Kubla Khan a stately pleasure dome decree…” The renowned poet Samuel Taylor Coleridge wrote the lines in 1797 while he was staying in a farmhouse in rural England. Coleridge was a prodigious user of the drug laudanum, and as the story goes, he fell asleep while reading a book about the Far East and actually dreamed the lines of a poem. Upon waking, Coleridge scribbled down the first 50 or so lines while still in an opium haze, but was interrupted when an unexpected visitor called on him about some business. Coleridge was only gone for an hour or so, but when he returned his vision for an epic 300-line poem had faded from memory. Coleridge attempted to get back to work, but eventually gave up out of frustration, and “Kubla Khan” remains perhaps the most famous unfinished poem ever written.

7. Dickens’ The Mystery of Edwin Drood

At the time of his death in 1870, A Tale Of Two Cities author Charles Dickens was perhaps the most celebrated writer in the English language. His last book was The Mystery Of Edwin Drood, a murder mystery that was in the process of being serialized in a popular magazine when Dickens died at the age of 58. Dickens was close to finishing the book, but he left behind no notes or plot sketches, so it has never been known for sure which character committed the murder that the story is based around. A number of writers have attempted to finish the book, often under very strange circumstances. The weirdest of all took place in 1873, when a man named Thomas James claimed he had written a conclusion to the book while possessed by the ghost of Charles Dickens. Many well-known writers praised James’ version as being remarkably similar to Dickens’ own writing style, and for years his take on the story was circulated in America as the definitive version of the book.