I have a question... I have looked at the pictures

I have a question... I have looked at the pictures of the construction of the new Large building. I noticed that it has no floor. I was just wondering why. I am from the deep south and when people build down here they lay a slab first. Do they do it different in that enviroonment and lay the floor last or is it that this type of operation isn't going to have a slab floor? Just curious. Thanks and GO FITX!!!