Updated as I work through the awesome NAND to Tetris series.
See main website,
http://www.nand2tetris.org
And Coursera classes,
https://www.coursera.org/course/nand2tetris1
https://www.coursera.org/course/nand2tetris2
From the Coursera page,
Build a modern computer system, starting from first principles. The course consists of six weekly hands-on projects that take you from constructing elementary logic gates all the way to building a fully functioning general purpose computer.