A friend of mine bought a house with doors on the 2nd floor that go nowhere except down. He even has one opening out and down to the outside.
He refers to them as "Mother-In-Law Doors".
The architect was supposedly inspired by a trip to Saint Johns Newfoundland where a lot of old houses on the extremely sharp hills the city is famous for, have 2nd floor door entries where there used to be a long stairs going down to the street for that side of the house. During the downturn, many stairs were left to fall down and not be replaced, leaving doors with a nasty drop if you were on the screech and forgot "where you were to."
I only saw a couple last time I was there but the economy is booming there now so I guess they rebuilt most of the stairs.