Supergirl Establishes Two Major Locations for the Arrowverse's Justice League in "Back From the Future"

The CW's Arrowverse of shows is officially operating in a post-"Crisis" world, and it's safe to say that each of the shows are in completely new territory. Supergirl has arguably experienced that in the biggest way, jumping from its previous Earth-38 to the new Earth-Prime. Tonight's episode played off of those repercussions in an array of different ways -- including finally establishing that yes, the Arrowverse does have a Hall of Justice. Spoilers for this week's episode of Supergirl, "Back From the Future Part One", below! Only look if you want to know!

The episode saw the long-awaited return of Winn Schott (Jeremy Jordan), who had previously traveled to the future to become a member of the Legion of Super-Heroes. What brought Winn back to the present-day was the goings-on of Lex Luthor (Jon Cryer), who had manipulated a doppelganger of Winn into committing evil deeds. As Winn, Melissa Benoist/Supergirl (Melissa Benoist), and company tried to figure out how to stop it, they were led to the office of J'onn J'onnz/Martian Manhunter (David Harewood). J'onn reveals that he has created a secret bunker inside of his office called The Tower, as an extra option for Earth-Prime's Justice League to meet together. While explaining this, J'onn mentions the main STAR Labs building that the group is operating out of -- which Winn says is called the "Hall of Justice" in the future.

While it was basically assumed that the building would be the Hall of Justice ever since it was first used in the "Invasion!" crossover, this serves as the first official confirmation of the building's name. In addition, the establishing of The Tower gives the group a space for smaller crossovers in the future -- or just for National City's heroes to use in the meantime.

"I would say I have 'ideas for ideas,' and I've sort of pitched to [The CW CEO] Mark Pedowitz and [executive producer] Greg Berlanti what, if left to my own devices, I would like to see us do," crossover producer Marc Guggenheim said of future Arrowverse crossovers earlier this month. "There is a rubric that is semi in place... and both Mark and Greg have signed off on that, and as we go onward, things will get more and more specific. I was emailing Mark just the other day, that we have to all get in a room together to talk about this. We typically do a post mortem about what went right, what went wrong, what did we learn... We always learn something."

Supergirl airs Sundays at 9/8c on The CW.