Staircase pondering

Just a quick one for today.
    I was doing some envisioning of passages in my underground world.  Sitting here, I was working out just how far ahead the chambers would have been planned and designed.  Would there be large open chambers, like in the Moria sequences from the LotR movies?  How the hell would you do it?  Who would design so many stairways without guard rails? (Okay, now I'm getting off track)
    This reminded me of the little castle defense trick of having tower staircases curl upward in the clockwise direction to give righties the advantage in defending the high places.  Yes, most of the world is right-handed and didn't they used to think lefties were devil worshipers or something?  Did "sinister" always have a sinister connotation?  Damn, off track again.
     It also reminded me of a tour I took of St. Vitus Cathedral, in Prague.  One of the really cool features was a paired staircase (think double helix).  Standing on the rooftop, their entrances were essentially side by side, but one exits inside the cathedral and the other outside (yes, there was a locked door on the outside one).  It was a little short on headspace, but it's a nice way to save materials and space.  Sorry to say, but it's not on the regular tour (it helps to teach the staff).
    The double helix design could be used for defensive purposes or for traffic control purposes.  It'd certainly be confusing for an attacker to be faced with this configuration.  With two adjacent staircases leading to two adjacent, but separate, rooms.  They could also lead to different levels within the complex, kind of like the local and express trains (or, more aptly, those elevators in high rises that only access the upper floors).  Hmmm kinda like that absurdly long stair that Gandalf climbs.  You might not even know there is a staircase twined to the one you know.  Thinking about it,  I'm sure it's a common element in Mystery novels, but I can't say I've read many.
    Oh, to continue the thought on defensive stairs, apparently they also used to design trap stairs.  No, I don't mean stairs that would drop you into a pit of spikes.  These would just have an stair with an uneven depth or height, which defenders would know, but attackers would trip up (since their attention is hopefully engaged by the defender's sword strokes).  Here, I just thought I was a clumsy tourist.  Seems it was a conspiracy after all.
    Alright, alright, that's enough.  As you can see, some of the details of construction can lead to beautiful little story details.  The child who always counts the steps in transit, may escape the vile attacking knight chasing him/her on the trick one.  Being a lefty has a number of advantages (as well as the potential stigma, depending on your world).  Choosing the right or the left-hand stair might be more important than we thought.  Knowing how the details fit together can help you envision your story, which may just help you tell it.  I know it works for me.