The first would be Isaac Asimov's Foundation trilogy, which I read when I was a teenager. I don't count the later prequels, since they are inferior works, and not worth bothering with. The longest would be C. P. Snow's Strangers and Brothers series (11 books), which I read when I was in my 30's.
The first would be Isaac Asimov's Foundation trilogy, which I read when I was a teenager. I don't count the later prequels, since they are inferior works, and not worth bothering with. The longest would be C. P. Snow's Strangers and Brothers series (11 books), which I read when I was in my 30's.