Isn't that the same Fortress set they used in Smallville? Regardless, here's the official description:
Kara travels to Superman’s Fortress of Solitude in hopes of learning how to defeat Indigo (Laura Vandervoort), a dangerous being who can transport via the Internet and who has a connection to Kara’s past. Also, James’s relationship with Lucy reaches a crossroads, on SUPERGIRL, Monday, Feb. 29 (8:00-9:00 PM, ET/PT) on the CBS Television Network.
Seeing Vandervoort return to this world should be a lot of fun, though visiting such an iconic Superman location without the Man of Steel having any sort of physical role in the series seems daft. Why not set Supergirl in a post "Death of Superman" world if him showing up is such an impossibility? It's beginning to get silly at this stage. Regardless, the show is definitely improving as time goes on, and this does sound like a fun instalment of the CBS series! Regardless, let us know your thoughts below.