Structure is partually collapsed, at least the outside of it and the ruined outside walls open more than one entry to the structure. You can't hear anything unusual (maze makes it's own sound time to time - Lilly told you that this most probably reflect maze transformation that is a reason for new monster appearance through the day)
Bellows superior dark vision allows him to see one corridor and a bigger room with a podium (not on the map yet as you can't understand details). But there are more entries.
I will fast forward - you go around, afraid to step inside and try to see as much as you can from the outside, This is more or less what you see, you have to choose which way to go - A, B, C, D or E. And do you go all together or split or ... basically describe me how you go in
I will not wait till input from all 4 of you before we move on. Take your time.
You may also attempt any information gathering before entering. Or anything. As a DM I will try to support you (as far as my imagination allows) at anything