How Roman Towns Were Built on Star-Aligned Grids
Published recently on the physics Web site, www.arXiv.org, maintained at Cornell University in Ithaca, New York, the research examined the orientation of virtually all Roman towns in Italy.
"It emerged that these towns were not laid out at random. On the contrary, they were planned following strong symbolic aspects, all linked to astronomy," Giulio Magli, of the mathematics department at Milan’s Polytechnic University, told Discovery News.
Part of a wider study published in Magli's book "Secrets of the Ancient Megalithic Towns," the research examined the orientation of some 38 towns in Italy.
Magli explained that ancient Roman writers, including Ovid and Plutarch, documented how the foundation of a new town took into account the flight of birds and astronomical references.
"However, the link between Roman towns and sky symbolism has never been fully investigated," Magli said.
The Romans founded many towns, or colonies, especially during Rome's Republican period and the first Imperial period, roughly from the 5th century B.C. to the 1st century A.D.
Their layout, inspired by the so-called castrum (a military camp), was always the same. The city consisted of a rectangle bounded by walls, with streets organized in a grid to form various residential quarters (insulae).
Two main roads, called cardus and decumanus, criss-crossed the whole city. Their intersection was the center of the social and religious life, while four main gates were placed at their ends.
"I did not take into consideration all the Roman towns, but only those in which at least the two main roads are still clearly discernible," Magli said.
For instance, the study did not examine the orientation of Pompeii. This city's two main roads are not obvious since the Romans later modified the city's layout.
Among towns with two clear main roads, Magli looked at the orientation of grids' axes in relation to the movement of the rising sun at the eastern horizon over the course of the year. He extracted this orientation from available archaeological maps or by using a precision magnetic compass on site.
"It emerged that the majority of Roman towns in Italy are aligned to sunrise, in relation to important sacred festivals or to the cardinal points," Magli said.
Basically, there are only three towns oriented toward the north: Pesaro, Rimini and Senigallia. These three towns also lie relatively close to the west coast of central Italy.
Only two towns in northern Italy — Verona and Vicenza — lie near the summer solstice sunrise line. Geographically close, they were founded in the same period.
All the other studied towns are oriented either within 10 degrees southeast of sunrise, or near the winter solstice sunrise.
"Given these results, we can say that Roman towns in Italy are not randomly oriented. This will help us understand what kind of astronomical knowledge the Romans had," Magli said.
"It is interesting research," Manuela Incerti, of Ferrara University's architecture department, said about the study. "It certainly opens the way to more extensive studies."
Article from: http://dsc.discovery.com/news/2007/05/08/romantowns_arc.html