Strongholds

From publisher blurb:

Revised and expanded, Castle Builder Reforged, Chapter 1 gives you the tools you need to bring your fantasy campaign’s buildings to life. What you’ll find inside is more than a collection of rooms you can throw together. Also included are questions to consider about your game’s most important structures and how best to use them as obstacles and abodes for your players’ characters.

A partial list of what you’ll find inside:

Sample maps
Rules for cost and time for building structures of any size
What buildings mean to different people
How to make your buildings memorable