Troy is about the Trojan War, which took place about 1000 BC.

Rating: 8/10 (1 February 2005)

As far as I know, this story has been made into a movie only once before... Robert Wise's Helen of Troy (1955). Those who think that Troy is a travesty of the original should be lashed to a mast and forced to watch Helen of Troy (for which the story of Achilles is over with in 20 minutes.)
I majored in Latin and classical literature, so I know the story of the Trojan War and the sources.
There are a few things the screenwriter did (to change the original) which can be forgiven... and something you, as the audience can do, which will improve the viewing experience.
The biggest problem for the screenwriter was to telescope a ten year war (which would have been incomprehensible to viewers) into a couple of weeks. Another problem was to take a story which was well known to those who heard it when it was first composed, 3,000 years ago or so, and make characters who could only appear for a few seconds into memorable characters.
As the first reviewer mentioned, the Trojan Horse does not appear in the Iliad. Neither does the death of Achilles (from an arrow in his Achilles' tendon). Could a modern audience stand a story about Troy, however, which does NOT contain the few things about the story which he DOES know? For me, far more troubling is the ending, where Paris escapes with Helen from the burning city. This was added to make a nice happy ending... but in fact, Helen returned to her husband. If you don't believe me, read Homer's Odyssey, where Telemachus visits Sparta to look for his father... and meets Menelaus reunited with his wife, Helen.
Cassandra may have a speaking part in the Iliad... I don't remember. Clytemnestra and her boyfriend did kill Agamemnon and Cassandra when they returned from the Trojan War, but did not serve his body up to their children... at least not in the Oresteia, by Aeschylus. Nor in Ovid's Metamorphoses, which goes over the same material. In Aeschylus' first play in the trilogy, the reasons for killing Agamemnon are complex... and fascinating.
Now if you know the original story and don't want to be disturbed by the screenwriter's changes, the logical thing to do is to watch Brad Pitt's masterful creation of Achilles, and Sean Bean's surprising Odysseus. The remaking of the story can be endured... until just after the funeral of Hector, when Odysseus watches one of his men carving a wooden horse. At that point, the wise person will walk out of the theater or turn off the video or DVD and be left with a fairly satisfying experience. Everything after that point is a letdown. It even SEEMS like Hollywood changes to the story.