Speaking of The Bagdad, at the corner of NE 37th and Hawthorne, it has two adjacent establishments "by crosswalk" (both edges signal-light protected) : Oasis to the north, and to the west what used to be a cool antique shop (now closer to Mt. Tabor), but currently remodeling to become a Peet's (as in "coffee shop").
That puts Peet's directly across from Starbucks, a competing coffee shop brand (around here, we tend to think of the former as being from California, the latter from Washington State).
Closing the square of this almost-perpendicular intersection (37th jags), Starbucks is across from Oasis. So there are the four vertices: B, P, S and O (Bagdad, Peet's, Starbucks, Oasis).
Ah, but what about the "kitty corner" relationships (so named for the lots of dead kittys who tried crossing that way?): edges SB and OP, don't they matter too?
In a typical tetrahedral model of "four establishments," you'd always expect, and give equal weight to, all six relationships. We wouldn't have this four-square distinction between "signal protected" and "illegal cross traffic."
But of course that's because we're imagining a spatial framework -- like I'm not saying every XY intersection needs two archway kitty-corner bridges (and if one did, you'd probably join 'em at the apex -- already more complicated than a tetrahedron then).
Still, this is a way you could think of spaceships to Mars or something. Giant tetrahedra with lots of coffee and beer going. Of course we'd put whole malls in each vertex, or maybe a school in one, a hospital in another...
Anyway, you catch my drift: once we're in "zero-gravity" (relative to Earth's very positive pull) we can start thinking less like squashed flatlander bugs (XY grid cities), and more like astronauts (cosmonauts, whatever -- like in 2001).