This infographic describes where you can actually visit fictional destinations. From UK flight search site Just the Flight, the fifty made up places span a number of categories including book, film, radio, games, television, comic books and myth.
When it comes to fictional destinations portrayed in movies or TV, the spots are typically where it was filmed. For example, Jaws's Amity Island was shot in Martha's Vineyard and Game of Thrones's Kings Landing is represented by Mdina, Malta. Winnie the Pooh fans can visit Ashdown Forest in England, which inspired the 100 Acre Woods. The Superman comics never name a specific location, but many believe Smallville is located in a rural Kansas town like Topeka.