I don't read many technical books but I value my print copy of "The Architecture of Open Source Applications," in which contributors to major open source projects like LLVM or Audacity walk the reader through the design and share their thoughts on how well the architecture works in practice.

The chapters are short and stand independently. In general the technical writing is pretty good, a skill that I am not surprised to find in project leaders.

It is free to read online: http://aosabook.org/en/index.html