A while ago I finished a late night project that had been ongoing for about half a year - reading all the 15 books in Isaac Asimov's so-called Foundation Universe. This includes his collections of robot short stories, the four robot novels, the three empire novels and the seven foundation novels. All the 15 books take place in the same universe starting with mankind's invention of robots, its expansion to colonization of the nearby stars with the help of robots, its subsequent establishment of a galactic empire, its fall and finally a glimpse of what might arise out of the rubble. And if one is already at it, it would also do no harm to read his End of Eternity as a sort of a prelude to the whole series - it is not directly related, but explores interesting topics with regard to time travel, which also give a hint of how the Foundation Universe might have become what it was to begin with.
I do have to admit that Asimov might not be the best writer in some respects. While reading, you do not necessarily always feel immersed in the characters and their local environment or problematics. Certain structures of storyline seem to repeat themselves from book to book. Often the immediate stories he tells might not seem too interesting and are rather simplistic. And he uses the word 'sardonic' way to often. But this is not what is most important or interesting about his works. It is the big picture that matters. Imagining the development of human kind from the not too distant future through tens of thousands of years into the future. Thinking about this and going through that imagination is something quite rewarding and inspiring. And it is for this reason that one should pick up the series. If you like this kind of stuff, it is really worth the time!