Western Civilization

Western Civilization is a metaphysical force which moves with the flow of civilization. It is the pure essence of mankind's culture and connects together everything that constitutes humanity's collective spirit and civilization. Occasionally referred to as the "flame" by immortals, demigods, and monsters this force moves with the center of human prosperity and influence, and was originally found in Greece. From there, it was carried by Zephyrus, the Western wind, to Rome, and then traveled across Europe, stopping in Germany, France, and Spain and ending up in Great Britain for a while. The current center of the "flame" is in America, precisely in New York City, with Olympus located above The Empire State Building.

The Olympians are intimately connected to Western Civilization as they are both its source and its embodiment. Since the rise of Greece, when the gods resided on the actual Mount Olympus, their home has also shifted location to correspond with the epicenter of human society. Thus, their palace now exists above the Empire State Building. This connection resulted in a profound effect on the gods and mortal civilization. Should Western Civilization decline, the gods would be severely weakened, and if the Olympian order was overthrown, then human civilization would unravel at the seams, degenerating into chaos.

The Lightning Thief
Chiron mentions Western Civilization while talking to Percy about the Greek gods and goddesses.

The Last Olympian
Dionysus tells Percy that if Olympus is destroyed, then Western Civilazation itself will perish.