Fortress of Solitude

The Fortress of Solitude is an occasional headquarters and sanctuary for Superman; serving as a place of refuge for him and his family away from the eyes of the public.

Over the years Superman has used the fortress as a repository for various instruments and powerful artifacts discovered in his adventures, keeping them in the fortress as a means of containing them or keeping them safe from greedy hands.

Background
Superman, on a self-imposed exile to space, was entrusted with a Kryptonian artifact called the Eradicator. Dedicated to preserving Krypton, this device built a new Fortress in the Antarctic as a precursor to recreating Krypton on Earth. Superman broke the Eradicator's control, but maintained the Fortress as a useful location to retire to in emergencies.

The Fortress was cast into the Phantom Zone as a result of a battle between a manipulated Superman's attempt to rule the world, Lex Luthor, and Dominus. The fortress was rebuilt by Steel, using a Spectral Nexus Apparatus to gather metaphysical traces of the destroyed Fortress, the "trace singularity" was transferred to an inter-dimensional portal called a "tesseract" for Superman to enter and leave at his whimsy. During an attempt by Superman to locate people who have been vanishing across the globe, Wonder Woman breached the Fortress in an attempt to confront him, causing the Fortress to self-destruct. Superman subsequently established a new Fortress in an ancient temple on a remote village in the Cordillera Del Condor Mountains, on the border of Ecuador and Peru.

Following the Infinite Crisis, Superman recovered a piece of Kryptonian sunstone. Learning that the sunstone had been sent with him from Krypton, Superman used it to construct a new Fortress in the Arctic.

Trivia

 * The Fortress first appeared in Action Comics #241 (June 1958)