In Terminal City the sunset is a shift change. All day the city has been inspected and patched and kept in time. As the light goes through the wires and over the rooftops, the Repair People put their brushes down, the crows head home, and the daytime systems hand the city over to the night.
You feel it without knowing why. Around sunset people want to stop working, walk, meet someone, eat, listen to something, make something, go out. That is not an accident. Maintenance is not the point of the city. Maintenance exists so that people can eventually stop working, and the sunset is the moment they are allowed to.
The Nocturnals start scouting. The Wire Choir shifts from daytime traffic to night music. The other city clocks in.