The joy of wander
I have a fun and simple game, you can play it when you travel: go to an unfamiliar city and try to reach a destination of yours. It can be the city center, the library, the museum, etc.
That's it really. But don't use any digital device for navigation, and don't ask someone to take you directly there :)
Another variation is to get yourself lost, then try to reach the point of departure. Take random buses and metro lines, walk into random alleys and stairs, visit random malls and shops, and if you can, take a bike.
You'll start paying more attention to street and district names and the surrounding environment.
Ask the natives for directions. It's a great conversation starter and an opportunity to practice a language.
If you want to find serendipity, this game is a good start. When I come to think about it, many of my favorite memories resulted from random events, and this game gives you just that.