Among all the nations of antiquity, altars, mounds, and temples were dedicated to the worship of the orb of day. The ruins of these sacred places yet remain, notable among them being the pyramids of Yucatan and Egypt, the snake mounds of the American Indians, the Zikkurats of Babylon and Chaldea, the round towers of Ireland, and the massive rings of uncut stone in Britain and Normandy. The Tower of Babel, which, according to the Scriptures, was built so that man might reach up to God, was probably an astronomical observatory. Many early priests and prophets, both pagan and Christian, were versed in astronomy and astrology; their writings are best understood when read in the light of these ancient sciences. With the growth of man's knowledge of the constitution and periodicity of the heavenly bodies, astronomical principles and terminology were introduced into his religious systems. The tutelary gods were given planetary thrones, the celestial bodies being named after the deities assigned to them. The fixed stars were divided into constellations, and through these constellations wandered the sun and its planets, the latter with their accompanying satellites.