What is the zoo of death and what are its levels?

In the book The Princess Bride written by: William Goldman. Their is a Zoo of Death with five levels of pure torture not to mention horror for those who enter. Made by Prince Humperdinck. The zoo was an underground dungeon. Located on the grounds of the castle in a remote area.

The first level:
Contained various creatures of speed. Wild dogs humming birds and cheetahs would be located here.

The second level:
 Creatures of immense strength. rhino's, anacondas, and crocodiles would be contained in this level.

The third level:
 Poisonous animals lurked about. This is where spitting cobras, death bats and jumping spiders were located.

The fourth level:
 Enemies of fear were contained in this level. Sucking squid, blood eagle and the shrieking tarantula tormented those in the fourth level.

The fifth level:
 Was left completely empty. The prince was hoping to put a creature as deadly as himself in this level.
 Later it contained Westley and the machine.