The Fortress of Solitude is a fictional fortress appearing in American comic books published by DC Comics, commonly in association with Superman. It is the place where Superman first learned about his true identity, heritage, and purpose on Earth. The fortress functions as a place of solace/occasional headquarters for Superman and is typically depicted as being in frozen tundra, away from civilization. Its predecessor, Superman's "Secret Citadel", first appeared in Superman #17, where it was said to be built into a mountain on the outskirts of Metropolis. By issue #58 it is referred to as the Fortress of Solitude, seems at a glance to be a freestanding castle, and is said to be located in a "polar waste". When the Fortress reappears in 1958 and for the first time takes center stage in a story, it is again an underground complex in a mountainous cliffside.

Superman is a superhero who appears in American comic books published by DC Comics. The character was created by writer Jerry Siegel and artist Joe Shuster, and debuted in the comic book Action Comics #1. Superman has been adapted to a number of other media, which includes radio serials, novels, films, television shows, theater, and video games.