Beautiful Architecture: Leading Thinkers Reveal the Hidden Beauty in Software Design by Diomidis Spinellis and Georgios Gousios
This book consists of a collection of fourteen essays on various aspects of computer architecture, ranging from system architecture to computer languages to enterprise architecture. The range of essays is impressive and the content is quite a good read.
I particularly enjoyed the chapters on the beauty of the architecture of the Smalltalk system with its hierarchy of classes and metaclasses, the Xen hypervisor, the Jikes runtime for Java and JPC, a virtualization system for x86 computers written in Java.
The Jikes chapter reminded me how much I enjoyed working on Lisp systems in the past, where the runtime was also written in the language that it implemented (making it metacircular). This meant that compiler optimisations affected both the user programs compiled for the system and the performance of the runtime itself. In addition, the system used the heap for holding the code vectors allowing the garbage collector to collect the space if the code were not longer accessible.
Most of the other essays were also interesting, covering general architecture and system design and a good article that explained why the EMACS extensibility model has been so successful.