The Parthenon itself replaced an older temple of Athena, which historians call the Pre-Parthenon or Older Parthenon, that was destroyed in the Persian invasion of 480 BC. The temple is archaeoastronomically aligned to the Hyades. While a sacred building dedicated to the city’s patron goddess, the Parthenon was actually used primarily as a treasury. For a time, it served as the treasury of the Delian League, which later became the Athenian Empire. In the final decade of the sixth century AD, the Parthenon was converted into a Christian church dedicated to the Virgin Mary.
The Theatre of Dionysus Eleuthereus is a major open-air theatre and one of the earliest preserved in Athens. It was used for festivals in honor of the god Dionysus. Greek theaters in antiquity were in many instances of huge proportions but, under ideal conditions of occupancy and weather, the acoustical properties approach perfection by modern test. We know that the theater of Dionysus in Athens could seat 17,000 spectators, and that the theater in Epidaurus can still accommodate 14,000 It is sometimes confused with the later and better-preserved Odeon of Herodes Atticus, located nearby on the southwest slope of the Acropolis. Some believed that Dionysus himself was responsible for its construction.