What are your favorite "boring" details you've built for your world?

So I was watching a video on the different types of electric power distribution lines for Japan, China, South Korea, and India. I was fascinated by the differences between them, and how they changed over time. Now I'm very tempted to create the same types of details for power lines in my world, just because.<br><br>What are similar small details you've built for your world, like "boring" details that didn't even cross your mind until you watched a video about them?<br><br>I'll show you mine if you show me yours.<br><br>Edit: I did not anticipate this much interest. Thanks to everyone for their comments. Thank you for being so nice to each other too. Keep it up.