Moonlight towers are lighting structures designed to illuminate areas of a city at night.The towers were popular in the late 19th century in cities across the United States and Europe; they were most common in the 1880s and 1890s. In some places they were used when standard street-lighting, using smaller, shorter, and more numerous lamps, were impractically expensive. In other places they were used in addition to gas street lighting. The towers were designed to illuminate areas often of several blocks at once. Arc lamps, known for their exceptionally bright and harsh light, were the most common method of illumination.