)
Had a top hat. Must have gone out in fashion, that one.
You said there where rows of seats, and then seats in the center? .. circular? .. perhaps in the form of a star?
To me, it personally sounds like an Order of the Eastern Star room that you came across, but I cannot say for sure.
Just remember there is nothing wrong about skeletons.. nor skulls or bones or skulls and bones together!

It is all symbolic and humble in meaning
and purpose, there is no devilry involved.
As far "locks" .. many lodges open there doors to the public, though it is of course up to them, I personally don't like the idea of mass amounts
of people parading through the building, but hey thats my opinion. It does raise awarness..
But my lodge not only opens its doors, it also gives guided tours and historic explanations.. we show them every temple in the building, York Rite,
Blue Lodge, Scottish Rite Theater, Eastern Star ect. People ask some, well sometimes just complete akward questions, some interesting, all come out
knowing something, some come out disapointed and I have honestly seen one man giving a tour accused of hiding all the real secret evil stuff (like our
goat?

) and showing them an "empty" room.
I cannot say for certain in regards to the lodge you visited as I have never been there.