of Superman, the "Fortress" was conspicuously absent, presumably because the series' aim was to explore the idea of Clark Kent being the true identity and Superman merely being the disguise (therefore, the character would have no use for an otherworldly fortress). In the earlier issues of the John Byrne revamp of Superman, the Fortress was also absent so the show was probably following suit. In the tradition of this approach, the Fortress of Solitude was the name of Clark Kent's childhood treehouse in season one episode "The Foundling". Smallville In Smallville, Jonathan Kent once referred to the loft space in the Kent farm's barn as the "Fortress of Solitude" since it was the place where the teenage Clark Kent usually preferred to be alone. In season 4's finale "Commencement", After Clark had united all of the Stones of Power (Air, Water, Fire) they created a super crystal, the "Crystal of Knowledge". Once he grabbed the crystal it transported him to an opening in the Arctic Circle where he threw the crystal into the snow thus creating the Fortress of Solitude. The fifth season premiere episode, Arrival, fully introduces a Fortress of Solitude that is almost identical, both in appearance and construction by self-replicating crystals, to that depicted in the original Superman movies. During the episode, Clark carries an injured Chloe Sullivan from the Fortress to a hospital in the Yukon, suggesting this is one of the nearest inhabited/medically proficient locations to the structure. An artificial intelligence built into the Fortress by Clark's biological father, Jor-El, would provide Clark with various 'Trials' throughout the series to help steer him toward his destiny as a symbol of hope for humanity. The Jor-El A.I. was, for the most part, omniscient, with the ability to send characters through time, open portals to alternate dimensions, and remove, restore and also transfer Clark's powers to other characters, seemingly at will. In later seasons, the Fortress is exposed as being vulnerable to other Kryptonian technology – namely Brainiac, and the Orb of Kandor. Lex Luthor would later use the Orb to revert the Fortress back into its original, handheld crystal form after becoming obsessed with Kryptonian conspiracy theories, and mistaking the structure for an alien invasion base. Lex also uses the orb to locate the fortress. The orb levitates and constructs a 3D globe of the world and isolates a circular section of Greenland. When the crystal