While Batman V Superman: Dawn of Justice is poised to continue Man of Steel's vision of the current big-screen Superman franchise as a grim and brooding affair, things are considerably lighter on the television side of what's now been confirmed as the DC Multiverse, where an earnestly upbeat Supergirl is busy building a reputation (and a weekly audience) independent of a mostly-offscreen version of her famous cousin. While decidedly charting its own identity, Supergirl hasn't been shy about incorporating elements of the classical Superman mythos, including Kryptonite and a grown-up "James" Olsen.
Now, another huge piece of the Superman canon is set to make its debut, as the upcoming episode "Solitude" will find Kara Zor-El visiting a certain famous Fortress.
According to an early synopsis for the episode, Kara (Melissa Benoist) will travel to Superman's (presumably unoccupied - at least for the moment) Fortress of Solitude in order to conduct research on defeating new villainess Indigo (Laura Vandervoot), a female equivalent to classic Superman nemesis Brainiac, who is set to become a new recurring threat on the series. Vandervoot, incidentally, previously played a version of Kara on Smallville, making her the second previous Supergirl to appear on the series after Helen Slater.
Early images of the set for the Fortress reveal that the series appears to be using the "crystal fortress" design from the 1978 Christopher Reeve Superman as its main visual reference. Whereas the interior construction of The Fortress has taken many forms over the years, the '78 movie version - which looks like ice but is actually formed of rapidly-growing crystals generated from a Kryptonian shard flung into the arctic tundra - is easily the live-action version most familiar to mainstream audiences. In Man of Steel, the Fortress was replaced by a repurposed Kryptonian spacecraft that was subsequently destroyed (along with pretty much everything else) at the conclusion of the film.
Traditionally (though not originally) depicted as a base of operations built into a hollow mountain and usually located somewhere in Antarctica, The Fortress of Solitude is one of the longest consistently-appearing aspects of the Superman mythology - though the name and basic concept were initially "borrowed" from pulp hero Doc Savage. Though it has taken many forms throughout the history of the character, the core concept of a hidden space for Superman to keep the physical aspects of his secret life (alien technology, the remains of his shuttle, etc) has remained. In most comics depictions, it has also functioned as a kind of museum/shrine to the lost culture of Krypton, frequently rendered to include large statues of Superman's birth parents and a globe of Krypton. In other periods it has functioned as Superman's version of The Batcave, housing scientific equipment used for crime-fighting research, a zoo for alien creatures, and at one point even an army of Superman look-alike robots designed to solve the "why does no one ever see him with Clark Kent?" problem.
This marks the latest deep-dive into DC Universe arcana for Supergirl, which is also preparing for an upcoming crossover with The Flash that will definitively cement it as part of a "multiverse," connecting initially-unrelated live-action and animated series within Warner Bros.' stable of DC Comics adaptations. Left unsaid (so far) is how far the connections plan to go. As yet, there don't appear to be any plans to bring Fox's Gotham into the mix, and there is no official talk yet of whether or not the DC films spinning out of Dawn of Justice will be shown to be reachable by universe-transcending characters like Flash.
Supergirl airs Mondays at 8 pm on CBS. "Solitude" is set to premiere Monday, February 29.