In a mall or somewhere with multiple basement levels, what is the proper way to designate each underground level?
We have: first floor, second floor, etc. for above ground floors.
Underground levels are usually referred to as B1, B2, etc.
If we are going to say something:
The food court is on ____.
What would be the full way to say B1?
The first basement floor
The first basement level
Or something else entirely?