Justice League of America #123 (October 1975) expanded the pre-Crisis DC Universe to include an "Earth Prime," which resembled the real one, and where DC's writers and artists channelled and occasionally controlled events on other Earths, where their characters "really" existed.
Earth-Prime later deviated from our world in other ways, and was eventually destroyed with the rest in Crisis on Infinite Earths. But, in Summer 2005, DC published DC Comics Presents as a tribute to influential writer/editor Julius Schwartz. Each issue based its main story on a classic Silver Age cover. DC Comics Presents the Flash (Jeph Loeb, Ed McGuiness, Dexter Vines, Dave Stewart) and DC Comics Presents the Atom (Dave Gibbons, Pat Oliffe, Livesay)feature Schwartz in a key role-- and the return of "our" other-dimensional Earth.

Thanks to Scott Slemmons (aka Jet-Poop and Scooter) for these images, and the idea for this page.