There are many types of yajñas. Śrauta yajña, Gṛhya yajña, Pañchamahāyañja, etc. etc. Here the term Śrauta yajña is of great interest for us. The concept of Śrauta yajña can be understood only in the context of Vedas and allied literature. The Vedas are the science of creation that takes place at three parallel levels, i.e. metaphysical, astrophysical and physical levels in the universe. The Śrauta yajña denotes nothing but the process of this creation. Nothing can be noblest and most excellent work than this act of creation. In the present book, a scientific explanation has been given to the fire-altars and Śrauta-yajñas like Agnisomīya Paśuyāga, Somayāga, Puruṣamedha, Aśvamedha, Gomedha, Avimedha, and Ajāmedha.