How can my neighbor possibly know all this?

I live in a small apartment building in Vienna, and for the most part, it’s been quiet and uneventful. But over the past few weeks, something’s been happening that’s made me feel like I’m being watched.

It started with small things. I’d come home and find my mail slightly out of place, like someone had gone through it. Then, I noticed that my trash bin in the hallway had been moved—just a few inches, but enough to make me wonder.

The real turning point was last week. I ran into my neighbor, an older man who lives across the hall. We’ve exchanged polite nods before, but this time, he stopped me and said, “I hope you enjoyed your trip to Salzburg last weekend.”

I immediately froze. I had gone to Salzburg, but I hadn’t told anyone in the building about it. When I asked how he knew, he just smiled and said, “Oh, I notice things.”

Since then, it’s gotten worse. He’ll make comments about what I’m wearing, what I’ve been cooking, even what time I usually go to bed. It’s like he’s keeping tabs on me, and I have no idea how he’s doing it.

I’ve started double-checking my locks and keeping my curtains closed, but it doesn’t feel like enough. I don’t want to overreact, but I can’t shake the feeling that something’s not right.

Has anyone else dealt with a neighbor like this? What should I do?