Best Software Architecture Books
I agree with the other responses to some extent – reading a book on C# syntax will not make you a good programmer, nor will reading a book on software architecture make you good at architecture. On the other hand, there were plenty of clever Roman engineers but any engineering student today can build things better than those Roman engineers. The difference is the knowledge we can apply.
So where do you get knowledge about software architecture? One place is your experience building systems. Another is conversations with other developers or reading their code. Yet another place is books. I am the author of a book on software architecture (Just Enough Software Architecture by George Fairbanks) but let me instead point you to some classics:
Software Architecture in Practice (Bass, Clements, Kazman). This book from the Software Engineering Institute (SEI) describes how architects should think about problems. It describes the importance of quality attributes (performance, security, modifiability, etc.) and how to make tradeoffs between them, since you cannot maximize all of them.
Documenting Software Architectures (lots of SEI/CMU authors). The title of this book is a bit scary, because many people are trying to avoid writing shelfware documents. But the wonderful thing about the book is that it describes the standard architectural styles / patterns, notations for describing structure and behavior, and a conceptual model of understanding architectures. All these are valuable even if you only ever sketch on a whiteboard.
Software Systems Architecture (Rosanski and Woods. Goes into detail about how to think about a system from multiple perspectives (views). What I like particularly is that it gives checklists for ensuring that a particular concern (say security) has been handled.
Essential Software Architecture (Gorton). Small, straightforward book on IT architecture. Covers the different kinds of things you’ll see (databases, event busses, app servers, etc.)
That’s just a short list and just because I didn’t list something doesn’t mean it’s a bad book. If you are looking something free to read immediately, I have three chapters of my book available for download on my website.