Architecture reporter Amy Peacock rounds up everything you need to know about building with cob, as part of Dezeen's latest editorial series focusing on the material. Cob is an earthen building material made from clay-rich earth, straw and water. The readily accessible nature of these ingredients means cob was one of the world's first construction materials, with many ancient cob buildings found around the world. In recent years architects, designers and researchers have revived the material as