This brass-and-steel "detector" doorlock, on display at Holland's Rijksmuseum, was made in 1680 or so. It has lots of clever features. To open and close the latch, you have to fiddle with the man's hat. The keyhole is hidden under the man's leg. It has a dial counter that lets you know how many times it has been unlocked, so the owner can tell if someone else opened it. When the lock has been opened 100 times as indicated on the dial, the main bolt can be locked, but not released until a tiny button on the man's chest is pressed, which resets the counter.
The inscription on the lock reads: "If I had the gift of tongue I would declare and do no wrong who you are that come by stealth to impair my master's wealth."
I hope they share the Arduino code for this.