I found it interesting to see that building floors in Australia are zero indexed. The first floor there is what Americans would call the second. Not sure why they chose to do it that way but it works fine in the real world.
That's not the case in all Australian buildings. Usually we call the ground floor "ground floor" (which you could argue is 0-indexed), and the floor above it is "the first floor". But there are a lot of buildings that follow the American style of "the ground floor is the first floor".
We also don't use negative numbers, basements are prefixed with a B, so B1 is like -1.
