Moonlight towers are lighting structures designed to illuminate areas of a city at night.
The structures were popular in the late nineteenth century among smaller cities across the United States and Europe, when standard street-lighting systems — using smaller, shorter, and more numerous lamps — were impractically expensive. The towers were designed to illuminate more city area at once via electric lighting. Arc lamps were the most common method of illumination, though they were known for their exceptionally bright and harsh light.
As regular street lighting grew more popular, the prevalence of moonlight tower systems began to wane.
When first installed, the towers were connected to their own electric generators at the Austin dam (near present day Tom Miller Dam). Over the years they were switched from their original carbon-arc lamps (which were exceedingly bright and time consuming to maintain) to incandescent lamps in the 1920s, and mercury vapor lamps in the 1930s. Mercury vapor lighting allowed the installation of a switch at each tower's base. During World War II, a central switch was installed, allowing citywide blackouts in case of air raids.
