Foundation Series/Foundation Bk 1/Foundation and Empire Bk 2/Second Foundation Bk 3/Foundations Edge Bk 4
A masterpiece of unsurpassed storytelling. I have read this series (now of 7 books) more than 5 times over the years and enjoyed them every time. inspiration for Star Wars and iRobot and so many more. A saga that keeps shifting and surprising and providing a wonderful and masterful twist toward the end.
I recommend this series to anyone with a passing interest in SF. It's not about gadgets. It's not about fantasy. It's all about people, humanity and what one possible future might hold for us.
 - Isaac Asimov)