Architectural façade lighting is the field where principles of architecture, interior design and lighting design are simultaneously applied to create lighting system sets for illuminating buildings facades, monuments, sculptures, and hardscaping fixtures. It can be achieved via the use of artificial or natural lights or by combining both. At nighttime external lighting brightens up the building exterior and sets it out from other cityscape structures; it emphasizes and enhances the shapes of façade relief. Architectural lighting can be complimented by external advertisement, especially rooftop structures or illuminated signs, by forming a solid architectural arrangement.