Segesta's claim to fame is its unfinished Doric temple, which is one of Europe's best preserved ancient monuments. At first sight, it looks like a normal temple, but the cella is missing (see the photos below, left and right), there are no metopes, and the columns are unfluted. This strongly suggests that the sanctuary has never been finished. As the architect appears to have been a Greek and the project appears to date to the years after the first Athenian intervention in Sicily (in 427-424), it may well be that the project was abandoned when Athens tried to conquer all of Sicily (415-413) and Segesta's pro-Athenian stance was no longer appreciated.
Alternatively, the sanctuary, which measures about 58x23 m, may have been intended as some sort of open court with a temple-like enclosure.