Grapestone, also known as cobblestone, refers to rounded stones used in construction. A rooftop illustration of grapestone would depict a design or layout using these rounded stones on a building's roof. This type of roofing is often seen in traditional architecture and can add a rustic aesthetic. Grapestone rooftops can be decorative or serve functional purposes, such as water drainage. The illustration would likely show the stones in an organized pattern, with details on how they are arranged and integrated into the roof structure.