After my PyCon lightning talk about software architecture, I got a couple of inquiries along the lines of, "So what kind of description are you actually looking for?" Michael Nygard's chapter in Beautiful Architecture
is a good example, but an even better one is Philip Ball's wonderful book Universe of Stone: A Biography of Chartres Cathedral
(subtitled Chartres Cathedral and the Invention of the Gothic
in paperback for some reason). It both describes and explains one of the world's great buildings, diving into minute detail where necessary, then zooming back to show how all the pieces (intellectual, historical, religious, and technological) fit together. Nothing like it exists for any piece of software---at least, nothing I've ever seen.