This is a place being overrun by thorns that aren't touched by fire or any other normal means to fight invasive plant life.
[In other words, whatever the city is like, Dark is just around the corner.]
Still, there are any number of reasons to close off a room. I'm not sure I'd call it hidden, or they'd have sealed off both of the back rooms with a wall across the hall, I'd think. Then you'd never notice the missing door.
[She's examining the wall, now, looking at it, feeling it with her fingers.]
The other rooms...their doors line up, don't they?
[She turns, and moves opposite of the door to the unpaired room.]
Shall we try knocking? Magic doors respond to that kind of thing, don't they?
Action
[In other words, whatever the city is like, Dark is just around the corner.]
Still, there are any number of reasons to close off a room. I'm not sure I'd call it hidden, or they'd have sealed off both of the back rooms with a wall across the hall, I'd think. Then you'd never notice the missing door.
[She's examining the wall, now, looking at it, feeling it with her fingers.]
The other rooms...their doors line up, don't they?
[She turns, and moves opposite of the door to the unpaired room.]
Shall we try knocking? Magic doors respond to that kind of thing, don't they?