Some of my inspiration books for building are:
Castles, Their Construction and History / Sidney Toy,
- Somewhat technical, (but that is just why I like it). It gives you lots of information and, more important, dimensions about al kinds of details.
The Medieval Fortress / J. E. Kaufmann & H.W. Kaufmann.
- Maybe easier to read. Many pictures, also some with dimensions. Castles from countries all over the world. (Even a Dutch one).
Some Dutch titles, of course.
The Internet is also a great source of information. A useful one among many others can be:
And I try to get as many as possible pictures, paintings, drawings and specifications, floor plans etc.
Above all you have to have some imagination to translate all those information into a MOC, of course.
But that is quite another story (topic)
"Too low they build, who build beneath the stars".
Edward Young / Night Thoughts.