Welcome to Sigil, the City of Doors, where virtually any place in the multiverse is but mere steps away, if you know the portal's location and its key.
Fun Fact: Annah's first spoken phrase to the Nameless One (the player character) is "Pike Off." Upon seeing him (but before you talk to her) she'll say "Looks like the Dusties lost one of their Deaders . . ." which is foreshadowing for some of the backstory.