A couple of days ago, I returned from a trip to Sicily, where I (armed with a camera and, more often than not, an ice-cream cone) enjoyed a whistle-stop tour of several Classical sites. One of the locations I visited was Segesta, which contains the remains of an incomplete Greek temple and a Greek theatre. There are also the remains of the agora (literally marketplace), from which stones were later taken away for other constructions.
According to Virgil, Segesta (known to the ancient Greeks as Egesta) was founded by Acestes and a group of Trojans who did not wish to continue following Aeneas on his journey to found the Roman civilisation; indeed, Thucydides (who states that Segesta was founded by Trojans) seems to agree with this. In any case, Segesta became an Elymian city (the Elymians being one of the three peoples native to Sicily), located on an important strategic point on the trade routes leading to Sardinia and Spain.
From 415 B.C., Sicily became involved in the Peloponnesian War. Segesta was already being threatened by the territorial ambitions of Selinunte (then Selinus) and therefore appealed to Athens for help. Segesta was able to persuade Athens of its wealth (and, implicitly, of the opportunities for Athenian empire-building in Sicily). Consequently, Athens began the catastrophic Sicilian expedition (as recorded by Thucydides).
We can tell that the temple (pictured above) is incomplete: the floor level of the temple is missing, as is an internal “nave”; moreover, the columns lack the fluting patterns that would have been added. There are several different theories as to why the temple is incomplete. Perhaps (controversially) the construction of the temple was only begun to demonstrate the wealth of Segesta to the Athenians, and construction was halted when Athenian aid was confirmed; alternatively, perhaps the town simply ran out of resources to build the temple. Furthermore, as a consequence of its incomplete nature, we do not know to which deity this temple was dedicated.