An alien organization led by the Curator and Apprentice-Prime that steals cities from the galaxy's past and present for scientific study and display (SF No. 190, Jul/Aug 1978: "The Museum of Eternity!" pts. I-III - "Somebody Stole My Town!"; "Doorways in the Sky!"; "Edge of Forever!"). The Preservers construct an interdimensional cage to display their captured cities, each isolated by an energy barrier impervious to humanoids. Among their collection is Jimmy Olsen's home town of Hartsdale and Kandor.
As the struggle to return the cities to their proper places ensues, President Jimmy Carter specifically requests the safety of Hartsdale, though any rescue attempt threatens Earth itself (SF No. 190, Jul/Aug 1978: "The Museum of Eternity!" pt. IV - "A Cage of Light!"). It takes the combined efforts of Superman, the second team of Nightwing and Flamebird, Krypto, the Phantom Zone Criminals, Jimmy Olsen, Lois Lane, and Supergirl to defeat the diabolical intentions of the Curator and the Preservers (SF No. 190, Jul/Aug 1978: "The Museum of Eternity!" pts. V-VI - "Fight with the Phantom Zone Fiends!"; "Finale").