Published about 40 years ago, this is quite out of date, and there are some glaring omissions, but still worth a read. Detailed maps of each area, some places covered in detail, and snapshots of the rest. Too large to use as a guidebook!
Review - Although this book is now years out of date it still makes for very interesting reading - it gives a lot of background information on these important historical and cultural buildings, and focuses in more details on a few of the major ones. It doesn't really discuss ruins, however, only those which are still standing. For example, Fotheringay and Kenninghall don't get a mention. Nevertheless, well worth reading if you have any interest in the history of buildings, or even history in general.
General Subject/s? - Castles / Houses / Buildings / Architecture / History / Palaces