Howstuffworks "The Pantheon"

With its remarkable dome, the Pantheon ranks as one of the great architectural marvels of ancient Rome. The building derives its beauty and harmony from its geometrical purity. Like an orange cut in half, the dome is a hemisphere. Unlike a halved orange, though, it is perfect: The dome's diameter is precisely the same as its height from the floor at about 142 feet.

In the center of the dome, a round eye opens to the sky. This oculus, an aperture measuring 27 feet across, admits a stream of sunlight -- the building's only source of illumination. During shadow and storm, the oculus reveals oddly beautiful special effects in the celestial fragment that appears.

The hole seems to connect the Pantheon to the sky and stars above -- an impression that is only fitting, as the building was dedicated to Rome's planetary deities. Completed around A.D. 120, the Pantheon was rededicated as a Christian church some 500 years later. This move no doubt helped to protect the site and probably explains why the Pantheon is the most complete and best-preserved building from imperial Rome.

The Pantheon's original bronze doors still survive, standing 24 feet high. In Roman days the interior was richly decorated. Niches held figures of deities, and a statue of Jupiter, Rome's primary god, stood in the center, illuminated at noon by a shaft of light from the oculus overhead.

The ancient dome is literally superlative: the largest cast-concrete construction on Earth until the 20th century. (At 142 feet across, it beats the dome of St. Peter's Basilica by six feet.) But how is the whole thing supported? No arches show, because they were embedded inside the 20-foot-thick walls, where they function like buttresses. And the dome's weight was reduced by using hollow, decorative coffering inside.

It is no wonder that the Pantheon, a surviving remnant of a world long vanished, still inspires architects to this day.

Here are links to dozens of other world-famous landmarks:

Abu Simbel, Egypt	Eiffel Tower, France	The Leaning Tower of Pisa, Italy	Roman and Georgian Bath, England
The Alhambra, Spain	Ellora Caves, India	Machu Picchu, Peru	St. Mark’s Basilica, Italy
Angkor Wat, Cambodia	The Forbidden City, China	Mont-St.-Michel, France	St. Paul’s Cathedral, England
Arc de Triomphe, France	The Golden Pavilion, Japan	Neuschwanstein Castle, Germany	St. Peter’s Basilica and the Sistine Chapel, Italy
Borobudur, Indonesia	The Great Buddha, Japan	Palace of Versailles, France	Shwedagon Pagoda, Myanmar
Chartres Cathedral, France	The Great Wall of China, China	The Pantheon, Italy	Stonehenge, England
Christ the Redeemer Statue, Brazil	Guggenheim Museum, Bilbao, Spain	The Parthenon and the Acropolis, Greece	Sydney Opera House, Australia
CN Tower, Canada	Hagia Sophia, Turkey	Petra, Jordan	The Taj Mahal, India
The Colosseum, Italy	Houses of Parliament, England	Pompeii, Italy	The Temple at Karnak, Egypt
The Dome of the Rock, Israel	The Kaaba and Al-Haram Mosque, Saudi Arabia	Potala Palace, China	The Terra-cotta Army, China
Easter Island Statues, Chile	Krak des Chevaliers, Syria	The Pyramids of Giza and the Great Sphinx, Egypt
Edinburgh Castle, Scotland	The Kremlin and Red Square, Russia	Pyramids of the Sun and Moon at Teotihuacán, Mexico

To learn more about other landmarks and vacation destinations, see:

ABOUT THE AUTHOR:

Jerry Camarillo Dunn, Jr., has worked with the National Geographic Society for more than 20 years, starting as a staff editor, writer, and columnist at Traveler magazine, then writing travel guides. His latest work is National Geographic Traveler: San Francisco. Dunn’s Smithsonian Guide to Historic America: The Rocky Mountain States has sold more than 100,000 copies. His travel pieces appear in newspapers such as the Chicago Tribune and The Boston Globe. Jerry Dunn's stories have won three Lowell Thomas Awards from the Society of American Travel Writers -- the highest honor in the field. He also wrote and hosted a pilot episode for a travel show produced by WGBH, Boston's public television station.