The city of the sun and Parthenope: classical astronomy and the planning of Neapolis, Magna Graecia

This paper investigates what may have been the cosmological and religious inspirations for the plan of the city of Parthenope-Neapolis (the historic centre of Naples, Italy), which was founded in the early fifth century BC by Greek colonists. Neapolis anticipated the strict orthogonal Hippodamian street grid plan. We argue that its geometry and geographical orientation was chosen so that Neapolis could be recognized as the city of Helios/Apollo (the sun-god of the Greeks) and Parthenope, the deified royal ancestor and/or the siren after whom the city was named. In fact, Neapolis's streets were cosmologically oriented using a sixteen-rayed hexadecagram geometry to emphasize Apollonian/solar cults. The city was also planned using a Pythagorean decagram/pentagram design with golden section proportions and inscribed geometries to symbolize the Harmony of the Spheres. These geometries were apparently inspired by the specific paths of the sun seen from the city on the solstices. Moreover, a sort of celestial light show on the spring and autumn equinoxes connected the sun, the Somma-Vesuvius volcano complex, Sant’ Elmo hill, the constellations of Taurus, Virgo/Parthenos and Aquila with the cult of Sebethos and Parthenope, the parent gods of Neapolis. Finally, Vitruvius's ideal city design appears to indicate that the novel and advanced planning of Neapolis served as a prototype for subsequent Greek and Roman cities.