Fantastica (called Fantasia in the films) is the vast and mystical universe within Michael Ende's novel titled The Neverending Story. It represents human imagination and survives soley on all the dreamers of the world. Its imperial capital is called The Ivory Tower which is also home to Fantastica's ruler the Childlike Empress.
It is impossible to give a definite Fantastican geography, as the oceans, it changes often. During the all life of an human that makes their wishes true using the potential of their imagination and the power of Fantastica, its geography responses to the volition of that human in particular, until that person abandons their dreams and phantasies, event that causes the slow destruction of Fantastica by The Nothing, or until another human starts to do the same thing with the power of Fantastica. Since that moment, Fantastica's geography suffers several changes, either by destruction or by reconstruction.