I have been noticing this mysterious door near our home opening onto open air above a cliff.
What happened? What is behind the door? Could people open the door and fall?
Is there a princess behind the door, a captive and waiting for her love to rescue her? Possibly Rapunzel of the fairy tale with her long golden tresses. Rapunzel, Rapunzel, let down your hair.
Or an imprisoned ghost.
Calling Daphne du Maurier, here is a plot starter.
Some novelist could write a book based on this strange door to nowhere. Nowhere but air.