Source: http://www.dl.ket.org/latin1/things/mythology/gods.htm 22nd paragraphDelphi under towering Parnassus, where Apollo's oracle was, plays an important part in mythology. Castalia was its sacred spring; Cephissus its river. It was held to be the center of the world, so many pilgrims came to it, from foreign countries as well as Greece. No other shrine rivaled it. The answers to the questions asked by the anxious seekers for Truth were delivered by a priestess who went into a trance before she spoke. The trance was supposed to be caused by a vapor rising from a deep cleft in the rock over which her seat was placed, a three legged stool, the tripod.
I know that "towering" means very tall but what about "under towering"?
It doesn't make sense to me. Would you please be kind enough to clarify the blue part to me?