The Aberdeen Bestiary: fantastic digitised illustrations.
A Bestiary is a collection of short descriptions about all sorts of animals, real and imaginary, birds and even rocks, accompanied by
a moralising explanation. Although it deals with the natural world it was never meant to be a scientific text and should not be read as such. Some observations may be quite accurate but they are given the same weight as totally fabulous accounts.
The Aberdeen Bestiary is considered to be one of the best examples of its type. The manuscript, written and illuminated in England around 1200, is of added interest since it contains notes, sketches and other evidence of the way it was designed and executed.
More imaginary creatures on Os seres imaginários (Portuguese post, but the links are in English).