In a window of the building on the west side of South Wall across from the Europa restaurant, there is a handmade sign.
Two signs, actually. But one at a time.
Sometimes it's "YES."
Sometimes it's "NO."
So what's the deal?
Something to do with romance? Espionage?
Sadly, the real explanation is a bit more mundane.
Turns out the signs are a signal to the UPS driver about whether there is something to pick up.