Within the 10 books comprising ‘De Architectura’, Vitruvius discusses the many and varied subjects which comprise the genre of Architecture. However, it is not a complete text for the subject.
From his own words we know that he copied or at least based his work on the texts of the authors listed in Book 7, chapter 7. Thus the simplest comment to be made is that he perhaps thought he was compiling an encyclopaedia of Roman design and building techniques. But that is not the resulting book.
That Vitruvius does not fully understand what he is writing or copying is amply illustrated in this text whilst sampling the data provided. I also endeavour to understand why, when writing such a treatise dedicated to Octavian/Augustus Caesar he is so parsimonious in his words, and why it takes until Book 6 for Vitruvius, writing about Architecture, to explain in a rather round-about way that his education included art and physics. If you are trying to influence or convince an emperor of your credentials, do it on page one, not after he has had to read 5 Books to find out if the author, (even though that author professes the he is known to Caesar), has the credentials to write the text. Therefore it is quite in order to ask why, and look at all of the other missing data, so carefully avoided.
This text does not analyse Book 5, Public Buildings, which is the subject of a third text referenced RmVt3. A short text reference RmVt2 discusses the Measure of Man, from Book 3, chapter 1.
The text is 26 A4 pages and there are 44 diagrams, some of which are full colour.