This book is the first complete study of the origin of geometry in India. In Ancient India, brick-built fire-altars (citi-s) were ordained for the Soma sacrifice, a Vedic rite, which led to the compilation of rule-books for making and arranging bricks. These volumes, called Śulbasūtra-s, represent the first available texts of both geometry and mensuration, and were composed from 600 BCE, although the actual practice goes back to c. 1500 BCE. This book begins by detailing the history of geometry in Egypt, Mesopotamia, and Greece, and shows that geometry everywhere starts with brick-built structures, rather than the measurement of land. It emphasizes that geometry in India, unlike in Greece, was side-based rather than angle-based. The text is profusely illustrated.