Write about something mysterious.
One time, I was at a gathering in someone’s apartment in Chicago and one of the hosts mentioned that there was a building next door that they had decided was a government front. It was a private residential building, presumably, but it looked very weird — it was a big concrete box with no windows and a weird big square industrial-looking front door. This wouldn’t be odd in a warehouse district, but this was Lincoln Park, a cute little neighborhood of traditional looking houses. The roommates who lived next to this box then talked in hushed voices about the various things that led them to conclude it must be a government front.
I was curious, so I went home and googled “weird box house in Lincoln Park” and similar until I dug up what it actually was. It was the first freestanding building in the US built by famous Japanese architect Tadao Ando. Ando is known for designing spaces that safeguard privacy from busy city environments and that use natural light creatively. This house looked like a dark concrete bunker from the street, but on the inside, it opened out into bright atriums and open air walkways.
That was years ago, but more recently an interesting-looking Ando gallery has been built next to the house (which I believe is still a private residence) to host exhibitions on architecture.
I never told my friends about the house’s actual story, because it would spoil the fun and if they wanted to know, they would have googled it themselves. So this is a good example of how (a) I am driven to ruin mysteries, and (b) the actual explanation for mysteries is frequently more interesting than the speculation (at least I personally found the actual explanation for this one more interesting).