Question: Can you please suggest some books on Software Architecture, which should talk about how to design software at module level and how those modules will interact. There are numerous books which talks about design patterns which are mostly low level details. I know low level details are also important, but I want list of good design architecture book. 

Please also suggest some books which talks about case studies of software architecture.

Answer: 
Where can 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](http://rhinoresearch.com/content/software-architecture-book)) but let me instead point you to some classics:

* [Software Architecture in Practice (Bass, Clements, Kazman)](https://rads.stackoverflow.com/amzn/click/com/0321154959). 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)](https://rads.stackoverflow.com/amzn/click/com/0321552687). 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)](https://rads.stackoverflow.com/amzn/click/com/0321112296). 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)](https://rads.stackoverflow.com/amzn/click/com/3540287132). 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](http://rhinoresearch.com/files/Just_Enough_Software_Architecture__Fairbanks_2010-demo.pdf) available for download on my website.
I'm not familiar with books that detail architectures and not design pattern. I mostly use the design books to get an understanding of how I would build such a system and I use sources such as [highscalability](http://highscalability.com/) to learn about the architecture of various companies, just look at the "all time favorites" tab on the right and you will see posts regarding the architecture of youtube, twitter, google, amazon, flickr and even [this site](http://highscalability.com/blog/2011/3/3/stack-overflow-architecture-update-now-at-95-million-page-vi.html)...