The answer to this question is open to some debate. Officially, the most expensive single film ever made was Spider Man 3 (2007) at a cost of $258 million. Tangled (2010) has been estimated to have cost $260 million, but that is an unofficial price tag. The Johnny Depp films Pirates of the Caribbean: Dead Man's Chest (2006) and Pirates of the Caribbean: At World's End (2007) were produced together at an estimated cost of $450-$525 million; it is estimated that At World's End cost $300 million alone. The official cost of Avatar (2009) was $237 million, but more recent estimates put the price at $280 million. With adjusted inflation costs, Cleopatra (1963), which cost $44 million, would be more than $300 million today. The most expensive film ever, with adjusted inflation costs, would be the Russian film War and Peace (a four-part movie released between 1966-1967); although the Russians claim an official cost of $9 million, it is estimated that it actually cost $100 million--or $700 million today.
Other expensive films were Harry Potter and the Half-Blood Prince (2009) at $250 million; The Chronicles of Narnia: Prince Caspian (2008) at $225 million; X-Men: The Last Stand (2006) at $210 million; Superman Returns (2006) at $209 million; and King Kong (2005) at $207 million. Titanic (1997) was the most expensive film made before the 21st century, with a price tag of $200 million.