Istanbul

Istanbul was a city in many universes.

In Reality Z-25 31-H, Catherine Maxwell tangled with the Skull's men in Istanbul on her way to Buranda to return Solomon's Diamond to the Koravi. (COMIC: Nula! Naked and Alone!)

One incarnation of Jenny Everywhere was a sea-farer who somehow traded cargo between “Byzantium, Constantinople and Istanbul”, with enough ocean between them that she could enjoy days-long sailing trips in-between each stop. The “Kim's friend” Jenny got a glimpse of this Jenny's life when she suffered from shifter hangover. (PROSE: Morning After)

Behind the scenes

In the real world, Byzantium, Constantinople and Istanbul were three names for the same city at different points in its history. It is unclear if this is simply not the case in the sea-faring Jenny's universe, or if, given Jenny's established space-time-hopping capabilities, something more complex was at play.