Mount Parnassus is where the Simurgh, Muses, Python, and Maenads reside. It has two peaks, one with the Tree of Seeds on which The Simurgh is perched most of the year, and the other of which the Tree of Immortality is on.
The Tree of Immorality is really not discussed much in the chronicles, but this giant tree's leaves apparently make a person immortal when eating, providing the person or creature stays on the mountain. The Tree of Seeds contains seeds from every plant to ever exist.
The Oracle's cave is where the oracle and the priests and preistesses of the oracle are. This cave has at least two entrances, because the clients use a different entrance from what the Python does. (Source Man from Mundania). The Python is the guardian of this cave.
These wild women eat try any male who appears on Parnassus. They drink from a spring that makes them extremely blood thirsty and are the eternal enemies of the Python. Occasionally, there are Maenads who either don't like the taste of blood, or get immune to it, such as Mae Maenad.
The python is a large snake that is the personification of what mortals fear and desire. When it was banished from the cave of the Oracle, it traveled up the peak with the Tree of Immortality on it and ate a seed.
Its gaze can freeze a woman. Although it eats Maenads, they come back to life when finished being digested.
The nine muses live in a palace on the mountain.
The Simurgh is the smartest creature in the universe. She is also the guardian of the tree of seeds. To reach her tree, most people seem to pass through the Palace of the Muses, but later some winged monsters can fly to see her.