Childhood's End

This book has everything that makes me love old sci-fi: A positivist view of humanity, open to the possibility of the truly strange, and progressive social and philosophical ideals underlying the story.
The basic premise is that alien overlords come down to Earth and presume to rule humanity. It turns out that they're much better at running the world than humans and that their motives seem to be altruistic. However, they are very secretive and refuse to reveal why they are so interested in helping humans.
This book is timeless, but it's also a beautiful reflection of popular ideas from the 50s and 60s, when interests in aliens, psychics and the paranormal really became popular. In Clarke's style, the characters are secondary and the plot doesn't follow a standard build-up, but there are so many brilliant concepts squished into this story that build-up really isn't necessary.
This book is very unique compared to modern stories. I recommend this to anyone who is looking to read something “different”.