Natural light with mirrors, lenses and water.
The sun is mightier than the bulb. We can magnify sunlight into a ventilation-like system of mirror tunnels.
Early humans used fire for light. This is a really cool light source too (at night, no sunlight). The same system can be lit by fire at night.
Fluids move in a randomized, chaotic fashion. This is cool. Therefore, a simple water layer can be added to the system for a happy effect.
Thin film is a more recent technology that can add cool advanced optical effects to both lenses and mirrors.