Spying and subterfuge in videos games and films sometimes show characters peering through keyholes to see into the room beyond. Was there a point in time at which keyholes were actually manufactured in such a way that you could see through to the adjacent room, or is this just an interesting fantasy mechanism?
closed as off-topic by user13123, Anaryl, justCal, John Dallman, Kobunite Mar 6 '17 at 8:06
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Requests for trivia or basic historical facts are off-topic if they can be easily answered by looking up the relevant topic on Wikipedia. We're trying to complement common historical references, not duplicate them." – Community, Anaryl, justCal, John Dallman, Kobunite
Yes, such keyholes are still the most common locks in some parts of the world: e.g my front door in the UK. More recent houses tend not to have this kind of lock, but it used to be the standard for house exterior doors.