Like the others in the series, this book answers the question "why are there so few worldbuilding pdfs out today?" There is little need for much else beyond this line, and this product in particular deserves the superlatives used to describe it.
It looks at the traditional concepts of historical Europe as they might apply to a generic fantasy world. It also incorporates the existence and effect of magic as far as possible without making assumptions that should be reserved for a GM to make. Mechanics are included for building many structures found in typical cultures.
Only if your tastes do not include a feudal, psuedo-European setting should you look past this pdf. I would also like to mention the excellent customer service I have received from the publisher in the past.
A Magical Medieval Society: Western Europe