ah, guess I was not clear with it, my bad

that barrier is only for the holes in the skull, if you look at the crude map:
the skull has various darkspots which would be holes in an normal skill (like eye sockets)
those are where the barriers are, this is because the holes go all the way into the main floor and act as lights during the day (as the main floor is underground)
its an anti-break in trick.
HOWEVER for all others, you have a huge ass front door which is only closed to public when there is a reason for (like, no one home or late at night (though guild members can still enter then))

so yeah, just send them though the front door ^^