Radioactivity in building materials is responsible for high levels of indoor exposure to ionizing radiation. The study of Radioactivity in raw materials used in manufacture of building materials is therefore of fundamental importance in setting regulations for the safe use of building materials. This book highlights measurement of radioactivity in Limestone and the effect dose rates emanating from the naturally occurring radioactive materials in the Limestone. The book therefore forms good basic knowledge for use by undergraduate students in the field on radiation protection.