Walling stone refers to natural stone used in the construction of walls, both for structural and aesthetic purposes. It has been a key material for centuries, from ancient stone structures like the Great Wall of China and the castles of Europe to modern dry-stone walling practices seen in rural and urban environments. Walling stones come in various types, including limestone, sandstone, granite, and slate, each with its unique characteristics that contribute to their strength, durability, and visual appeal.