I know there are other examples of cities in bottles (Superman's Kandor, for instance), but I wonder if this one is inspired by the story in Sandman #50 “Ramadan”, wherein the sultan of a mythical, magical Baghdad bargains with the Lord of Dreams to keep the city safe for eternity, which the Endless achieves by trapping the city in a bottle in the dream realm, leaving only a mundane version of Baghdad in the real world, devoid of all the magic and wonder of the original... no further cards from that original reality can be played, paraphrasing the card, except in dreams...