Also important is the west pediment, depicting the contest between Athena and Poseidon for the position of patron divinity of Athens. Athena gave the city an olive tree, and Poseidon struck the earth with his trident, causing a salt spring to burst forth. The winner was Athena. Most treatments of the story seem to regard this as a fairly straightforward sort of thing, but actually there is a fairly complex symbolism involved in it, inasmuch as the sea was really as important in Athenian life as the olive.
This leads to reconstructions of the entire west pediment, as reconstructed in the Nashville Parthenon (near middle of website) and of its central scene (at end of a number of nice images of the Parthenon).