The space below that circular opening was entirely filled with water!
There were no steps up or down, just circular openings in both the stone floor and ceiling.
Upon the opposite side of the room was a circular opening guarded by two warriors.
He pointed the flashlight up at the circular opening in the ceiling.
He could hear the voices of the two men coming through the circular opening above his bent head.
This is the central circular opening in the colored part of the eye - also called the iris.
The ceiling level fell and the floor rose to form a tight circular opening.
It issued from the circular opening in the ceiling of the stone room.
He took the third man back with him to the circular opening of the well.
She twisted and dove through a circular opening in the "floor."