The Pantheon was a Roman sundial?

The mystery has always surrounded what lies behind the unusual design of the Pantheon, a large temple in the heart of Rome, built by Emperor Hadrian.

Now experts have developed an intriguing theory, namely that the temple acted as a colossal sundial, with a beam of light illuminating its enormous entrance at the precise moment when the emperor entered the building.

Completed in 128 AD, the hemispherical dome of the Pantheon is perforated by a circular hole of 9 meters known as ' oculus '. It provides the building the only source of natural light.

Giulio Magli, professor of archaeoastronomy at Milan Polytechnic, and Robert Hannah, a scholar of classical literature at the University of Otago in New Zealand, they discovered that just at midday during the March equinox, a circular beam of light shines through the oculus and illuminates the imposing entrance of the Pantheon.

The two work on this theory since 2009, but recently they released all their research in the journal Numen.

The precise calculations made ​​in the positioning and construction of the Pantheon have made it possible that the size and shape of the light beam correspond perfectly, until the last centimeter, in a semicircular stone arch above the door.

A similar effect is seen on April 21, the day that the Romans celebrated as the date of foundation of the city, at noon when the light beam strikes a metal grille over the door, illuminating the backyard porch.

These effects would be seen by the Romans as elevation of the emperor in the realm of the gods - a cosmological affirmation of his divine power coming into the building, which was used as a courtroom, as well as a place of worship.

In fact, he was "invited" by the sun to enter the Pantheon, which, as the name suggests, it was dedicated to the most important deities of the Roman world.

"The emperor would have been illuminated by lights like in a film studio," says Magli. " The Romans believed that the relationship between the emperor and the celestial spheres reached its peak during the equinoxes. It would be a glorification of the power of the emperor and Rome itself. "

The Sun had a special meaning for the Romans, as he had for the ancient Egyptians. The god Apollo was associated with the Sun, and the Emperor Nero was depicted as the sun god greek helium in a giant statue, the Colossus of Nero.

The conservation of the Pantheon is due to the conversion into the church during the seventh century, when the Byzantine emperor Phocas gave it to Pope.

The building retains its original bronze doors and its marble columns, material partially extracted in the Egyptian desert and transported by ship along the Nile and across the Mediterranean to Rome.

Today, the Pantheon contains the tombs of King Vittorio Emanuele II, the first king of Italy, and Raphael.

Other legends and curiosities

• According to popular tradition, the Roman shallow moat that surrounds the building of the Pantheon was not excavated by human hands. It is said that one day the devil was waiting for the pledge of magician Peter Bailardo for his services. Once it leaves the Pantheon paid the devil with only four nuts and then took refuge in the church. So the devil, angry at the indignity suffered sank into the flames in the bowels of the Earth to create furrows called just " moat of the devil."

• Legend has it that it was built after the appearance of Cybele (comparable to the Virgin Mary to Christians), a goddess who asked him to build a temple even providing instructions on how it must have

• The weight of each stone construction Pantheon reaches up to 90 tons. Marble slabs that are more than 2000 years ago come from Egypt for the erection of the new Roman temple.

• The entire building of the Pantheon can be inscribed in a perfect sphere. The building height is equal to its diameter and measuring 43.44 m to 43.44 m. This feature meets the criteria of classical architecture balanced and stable. In the Pantheon these principles are summarized by the harmony of lines and perfect calculation of the geometry of the masses.

• The dome of the Pantheon is built in concrete at the time of building the largest ever built in masonry. It was the work of reconstruction in 128 AD The building suffered under the rule of Emperor Hadrian. Until the completion of Brunelleschi's Dome (1436) the dome of the Pantheon was the largest ever built.

• The dome was so great that it was considered impossible that had been created by human hands for this was also called the Devil's Dome.