To remodel a "Mud Set" bathroom is very labor intensive. The following pictures will provide you with a visual of how they were constructed. It takes major labor to remove these old bathrooms

This shows you the thickness of the floor

This is the floor Joist, notice it is pointed and will need to be "Sistered" before the new sub-floor is installed

New pipes are "Roughed In"

New Marble floor installed

Completed bathroom