Where is this jail cell? What’s the city name, vibe, etc?
That's a bad question, because it draws blanks, not leaves them. Better questions would be:
- «Fighter, how big is the city? Is it more like a village, or something closer to a big, prosperous metropolis?»
- «Rogue, which known criminal is doing his time in some other part of this jail?»
- «Barbarian, you've been there quite a lot for your drunken fights, did you? Name one guard who's here now, you know each other a little too well!»
- «Wizard, for what breakthrough the local magical academy is known?»
- «Cleric, which religion do they preach here?», and, optionally, «Which part of it you would never agree with?»
Don't just ask «what's the city vibe», get them something to build from!