I noticed something kind of odd in one of the neighborhood where I ride my bike in the morning, It's a combination of old houses that look like they've been there since like the '70s or '80s and newer houses that probably aren't even 20 years old mixed together, sometimes right next to each other. There's one street where it's literally old house, new house, old house, new house, down the last part of the street.
I'm thinking what is that the old houses would have built at a time where there was nothing out in this area. so they were able to be a lot more spread out, with tons of space between them, but then as the city absorbed the area, new people came in and filled in the empty spaces with new houses.