There are barn doors
And there are revolving doors
Doors in the rudders of big ships
And there are revolving doors
There are doors that open by themselves
There are sliding doors
And there are secret doors
There are doors that lock
And doors that don't
There are doors that let you in and out
But never open
And there are trapdoors
That you can't come back from
- Radiohead's song Pulk/Pull Revolving Doors