“Rhapsody in blue”—the blue color in architecture and the built environment: traditions and contemporary applications

The main goal of this article is to summarize and present the most important facts concerning the use of the blue color in the built environment, considering its symbolic, functional, and decorative aspects. This monograph of color is aimed to contribute to a better understanding and clarify the place and meaning of the blue color in the architectural space and allow architects to use this color with greater awareness of its characteristic features in the historical context. The results of the detailed analysis of more than 200 blue buildings, collected by the author since 2006, are grouped into seven main thematic sections, which express different ways of applying blue in the architectural space: as a symbol/idea, the color of the sky, as traditional, contrast, and material color, as a visual attribute and brand color, and last but not least as the color of the light. The main conclusion is that, although the rationales for using blue color in architecture were diverse, symbolic and aesthetic considerations prevailed. As the dominating color of the sky and water, blue is considered the most intangible of all hues in architecture. Also, as a worldwide attribute of divinity, connected with Heaven as the domicile of deities and gods, it has received a considerable spiritual load. The universality of this symbolism, combined with the high cost of pigments, has given the blue color its unique and exclusive value. Even nowadays, despite the greater availability of blue materials and colorants, blue has not become a prevalent color in architecture. On the contrary, its visual impact, both in glass curtain walls and in night illuminations, still emphasizes its immateriality and reference to spiritual symbolism.