A Review of History and Architecture of Roofing Slates: Impact on the Unesco World Heritage List

This review explores the historical, architectural, and cultural significance of roofing slates, emphasizing their influence on global heritage as reflected in UNESCO World Heritage sites. Tracing their use from Roman times through the Middle Ages, Industrial Revolution, and into modern architecture, the study highlights how slate has served both functional and symbolic roles in building design. Focus is given to European quarries, notably in Wales, France, Germany, and Spain, with Spain currently leading global production. The work also investigates the recognition of roofing slates as IUGS Heritage Stones and their overlap with UNESCO-listed monuments, affirming their heritage value. A deep learning model employing convolutional neural networks was developed to identify slate roofs from imagery, achieving over 85% accuracy. Of the 1248 UNESCO sites (December 2025), 86 (7%) feature roofing slate, underscoring its architectural prominence. The study also warns against the use of artificial imitations in heritage preservation and advocates for the continued valorization of natural slate in cultural conservation efforts.