Other Worlds Than These

What if you could not only travel to any location in our own world, but to any possible world?
We can all imagine such "other worlds" be they worlds just slightly different than our own or worlds full of magic and wonder but it is only in fiction that we can travel to them. From The Wizard of Oz to The Dark Tower, from Philip Pullman to C.S. Lewis, there is a rich tradition of this kind of fiction in the fantasy genre, but never before have the best parallel world stories and portal fantasies in the science fiction genre (of those published prior to 2012) been collected in a single volume until now.
"When I read The Chronicles of Narnia as a child, it didn’t so much introduce me to the idea that there was another world as confirm my already grave suspicions on the subject. Even at the tender age of eight I was as I suspect you were, and are, if you’re reading this book one of reality’s natural critics. Oh, I knew that the real world had its good points. One must be charitable after all. Candy, for example, and cats, and hot baths. But by and large the material was just a bit thin. The jokes weren’t funny, the catering was uneven, and the less said about one’s fellow players the better. I had a powerful urge to see what was on in the next theater over. Until I read The Lion, the Witch and the Wardrobe and Alice’s Adventures in Wonderland, and The Phantom Tollbooth, and The Wonderful Wizard of Oz, and The Chronicles of Amber I thought I was the only one who felt that way. Of course this can’t be all there is: this ludicrous excuse for a universe can only be a rough draft, a temporary substitute, the amateur opening act before the main event, which will be more magical, more exciting, more meaningful, more ecologically sound and otherwise superior in every way."