Cities have secrets. Their ways and nooks and systems. I think we only get to learn a few of them, really. There are probably people out there who have something approaching a holistic understanding of cities, but it's such a tangled nexus of disciplines and secrets, I struggle to imagine anyone has the truest pictures at this points.
Cities are our triumph and our folly. Absurd hyperobjects which we (some of us) live as part of, with their structural complexity having grown and grown in multidimensional layers.
Look at the street furniture around you. The manhole covers and junction boxes. The strange, unexplained objects which surely must have some purpose. The sprayed markings on the pavement. The little riveted metal points around the place.
They aren't actually arcane, and plenty of people understand them -- though I expect most who pass by and benefit them have no idea what they are. A few years ago, I went a bit mad in Toronto and did a bunch of writing about this.
This is part of what I mean when I say 'secrets' -- codes and systems that we can learn to read in part.
I'm also, as I so often am, talking about birds. There's a street near my house which is really good for birds. Starting in early summer, swallows come to nest in the roofs of the houses (apparently, they have been doing so for more than twenty years). There are dozens of little cavities in which starlings nest, easy to miss until you see them flying in and out to build or to feed their young. When you watch pigeons long enough, you can identify the spots they're going to love to lurk.
Infrastructure. Animals' sharing of 'our' space. Architecture. Logistics. Desire lines. Movement patterns. Markets. Green spaces. Clay.
I always want to learn more. I think a lot of what I want to learn is really about cities. I know a lot more now than I did a few years ago -- can see and read a lot more of the city. But it's nothing, really. Peering through a gap in a hedge at something strange and beautiful.