Old stones door.

[Disco]

Dunno if this is a bug. But I have seen it open on several ocasions, perhaps its able to be picked?

[Bobbybrown]

The door is now allowed to be open, when davan was mayor he repealed the summerset act.

[NetherGonnaGiveYouUp]

It was sealed once again after Redthorn was killed, either it's a bug or the DM's haven't gotten around to making sure it is locked again as standard.

[Jagged]

The doors can be opened from the inside, this is why.

[Bonhomie]

^ locked from outside, open from inside