We found this basement entrance hidden under a carpeted trap door on Photobucket. It appears the door conceals the seldom used basement and allows for the space above to be used as a small office area when closed.
An installation like this goes against some building codes in the US, and could cause allow for trapping someone in the basement if correct precautions aren’t taken. Still, it’s a fun use of space and allows for complete concealment of the downstairs to guests that aren’t aware.