Why was the Parthenon highly regarded?

That the Greeks established fortresses on high places for defence and refuge (acropolis) and as the city-state developed built their temples there . One of the temples was dedicated to the patron god of the city who protected it - in this case the goddess Parthenos (virgin) Athena after whom the city was named. The temple was also the repository for the city's treasure as they would not dare steal from the goddess, and was also a refuge for those seeking protection from the goddess, as no one would touch someone under her protection.