Within our fantasy worlds are massive cites. There are lots of problems with the scale of some of these cities — they need farms, roads, and light because residents are up at all hours. Settings like Ravnica and Eberron deal with the largest cites via magic. Those worlds with less magic manage metropolises with some magic, some magically imbued races and hand-waving. One of those hands we can wave relates to light.
Magic is the simple way to add light to cities. Another way to have them with some level of light for safety and to encourage all races to reside within is via a public lantern system. For about 150 years this was the process in Western Europe and Northeast America. People would go through and light lanterns along the street. Those shops and establishments that wanted business in the evening or early morning would do the same.
These workers would live split lives as early risers and night owls.
Let’s crank all of this up to d20 and make them potential heroes. Meet the Lamplighter, for “in darkness there is light.”