I am going to be honest, here: I didn’t ever read the comics, nor have I followed a terrible amount of the Superman movies. I can, however, appreciate a gorgeous LEGO creation even if I didn’t recognize the reference.
I’ll let the builder, Ken Robichaud, do the explaining:
Once the capital city of Krypton, it and its inhabitants were shrunk and preserved from the planets eventual destruction by the villainous Brainiac.
Kept safe in Superman’s Fortress of Solitude after its liberation from Brainiac’s ship, it became part of the Last Son of Krypton’s collection of unique and precious items and lifeforms from across the universe.
I’d recommend checking out his other comic book builds, of which there are just too many great ones to choose from! You can find all of them here.