This reading of the Pantheon is based on Pythagorean literary and mathematical traditions available at the time of its construction, especially to one so captivated by Greek learning, mysteries, astrology and mathematics as Hadrian. By counting the essential parts of the building and relating those numbers to its shape and function, the structure clearly "reads" as the Marriage of the Sun and the Moon. Hadrian's horoscope, well known to scholars of classical astrology, sets forth the time of his birth as occurring at a moment of "coincidence" of the Sun and the Moon. His earliest biographers underline his special interest in the Sun and the Moon which corresponded with his Pythagorean interests. Other documents (one of which may have been authored by Hadrian himself) collaborate to persuasively suggest that the Pantheon was built by Hadrian not only to honor himself in language far more effective than that which a statue would have allowed, but to legitimize his reign which was in serious trouble at the time the Pantheon was designed. This paper does not purport to hold an "answer" to the meaning of the Pantheon. Rather it aims to work with hitherto unexplored materials that appear to hold promise as sources that may provide new avenues of investigation for study of this important building for which the cosmological significance of numbers - a time honored tradition in Greek learning - can widen our knowledge.