It's not just the architecture. But the sunlit, overgrown alleys are heartbreaking, the logistics infrastructure is vast, cool, and indifferent, and Steven King called the vacant rowhouses one of the scariest places he's ever seen.
The great thing about The Wire is the interrelationships. it's about the way small groups can hold and control urban structures by taking the key spaces, the stairwells in the towers, the courtyards in the garden apartments, and the corners in the streets. It's about the relationship between power and urbanism, in districts, wards, localities ...
It makes the city legible and comprehensible as a network of subcultures, a network of networks, and it presents these networks in a way that anyone can understand and relate to. It's not like these tropes haven't been run through before, we've all seen drama about cops, drug dealers, or politicians in the postindustrial landscape. But this is the first place that shows all the networks together, laid out on a plane like the speed dial numbers in tapped cellphones, and they're all the more traceable for their interconnections, parallels and isomorphisms. The show represents life, not by stealing from it, but by mirroring and modeling it.
It's not just the realism. The realism is great, but realism is a moving target. Being in Baltimore, or any city, with The Wire echoing in your head, makes the social landscape of developers, police, city councilmen and corner kids understandable without being consumeable. You kind of feel, for better or worse, like you know these people. You've gotten a look at the underlying diagrams, just enough to let you know that there are whole worlds built off them to get lost in.
Realism is assembled and eventually decays: Expression -> Story -> Literature -> Cliche. Signifiers are plucked and sold like blossoms from a tree. But the diagrams remain, and resist simple interpretation.
[Edit - Oh yeah, and the soundtrack comes out in January]