"Professor Ross Anderson from the University of Cambridge in the UK is one of the world's leading authorities on security. And we're not just talking IT and computers, but also the security of everything from railway stations to nuclear power plants. Four years ago, he published an amazing book about all this, which runs to over 1000 pages. Now, it's available as a free download. And it's a fascinating read."
Note: each chapter needs to be downloaded individually.
Full credit for find & description to HUKD