A puzzle below

It’s not the first place you’d expect to run into an architect, a shrink, a poet and a nuclear physicist: 23 feet below ground, in a shadowy labyrinth of volcanic rock that once may have held the ashes of kings, the bodies of sacrificed children or an oracle whose cryptic pronouncements swayed the fate of 100,000 people.

Then there’s this imposing thought: Directly above you, held in place largely by its sheer brute mass, is several million tons of stone. Lots of bad earthquake jokes are heard in the tunnel beneath the second-largest pyramid in the Western world.

But just as you’ve bumped your head on the low ceiling for the fourth or fifth time, and your fingers are struggling to Braille-read the wall’s jagged contours, a flashlight flicks on. In its pale, steady glow, archeologist Jesus Torres Peralta is the picture of tranquillity. Listen, he says, to that perfect, all-encompassing stillness. Notice how easy it is to breath. Feel the cool air enfold you in its deep, ancestral embrace.

“It’s the sensation of being in the Tierra Madre” -- the Earth Mother, says Torres, his words barely rising above a whisper. “It’s a universal myth, the sense of arriving at the promised land.”

Most of the thousands of people who visit this ancient pre-Columbian city each year touch only its outer skin. They amble along the Avenue of the Dead, the main thoroughfare, and scramble up the steps of its two colossal monuments, the Pyramid of the Sun and the Pyramid of the Moon. On warm Sunday afternoons, the waiting lines for these summits can be as long as at Disneyland’s Splash Mountain.

But there’s another, far less visible face of Teotihuacan (pronounced tay-oh-tee-wah-KAHN), once the greatest metropolis in the Americas and still a sacred spot for millions of Mexicans seeking spiritual renewal. It’s a pitch-black face whose historic features have only begun to emerge from the mists of legend since it was rediscovered in recent decades. It’s the face of an older, even more enigmatic Teotihuacan than the one that attained its golden age around AD 200 and thrived for roughly the next 350 years, until its inhabitants mysteriously vanished, centuries before the Aztecs migrated to this region or the conquistadors set foot in the New World.

This is the subterranean, subconscious Teotihuacan, a hidden sub-city of caves, burial pits, secret chambers and serpentine corridors, a Jungian maze of mythic origin where small but growing numbers of Mexicans are returning to discover who they are, both as individuals and as a people.

And of all the underground passages scattered throughout Teotihuacan, the twisting 110-meter tunnel-chamber beneath the Pyramid of the Sun is thought to be one of the oldest and, probably, the most important. Some scholars believe that the ancient inhabitants of the Valley of Mexico worshiped this tunnel as their ancestral home, as a kind of gigantic geological birth canal -- literally, the Mother of All Tunnels -- and later built the rest of Teotihuacan around it.

Other scholars, including archeologist Linda Manzanilla, Mexico’s leading expert on Teotihuacan, argue that the tunnel was designed as a representation of the underworld in the vast, cosmologically inspired layout of Teotihuacan. Some think the tunnel also may have been a sanctuary where children were sacrificed by drowning to Tlaloc, the god of water and the underworld. Other theories about its purposes abound: a crypt for the bodies or ashes of dead rulers, a storehouse for the skins of flayed victims, an oracle’s lair.

Then there’s the really big question, the one sure to start a debate over the wine and cheese spread at the next archeologists convention: Is it really a man-made tunnel at all or a naturally formed cave?

What no one seems to dispute is that the tunnel, grotto, cave or whatever it is played an exalted role in the meticulously planned city of Teotihuacan. Though it hasn’t yet yielded any dazzling artifacts or treasure-trove of telltale human remains, the tunnel endures as a tantalizing void, pregnant with possibilities. “The tunnel underneath the Pyramid of the Sun had a special spiritual significance,” Manzanilla says with finality. “It was the most important tunnel.”

Today, this sunless, souvenir-free part of Teotihuacan is being explored not only by archeologists, geologists and anthropologists but also by a variety of writers, designers, scientists and others hoping to use Mexico’s vibrant past to illuminate its complex and problem-laden present.

“The Mexican people believe in the affairs of their ancestors,” said Nadja Comorera Pfeiffer, a Mexico City psychologist, explaining what had drawn her, along with half a dozen other invited guests, to explore the tunnel and surrounding ruins one day last week. “I wanted to investigate a place in which is the beginning.”

A world apart

Mexico has long had an ambivalent relationship with its indigenous past. For centuries after the Spanish conquest, many native sites were either abandoned to nature or taken apart, with their materials used to construct new churches and palaces. Some churches were built on top of the ruined temples, symbolically obliterating the old pagan gods.

Teotihuacan also fell into a long period of neglect, but today it tops the typical tourist’s must-see list of sights around Mexico City and draws researchers from around the globe. Though only a 40-minute car ride through the drab concrete slums northeast of the modern-day capital, Teotihuacan is a serene, smog-free world apart.

Although much of the 9-square-mile city is accessible to the public, the tunnel below the Pyramid of the Sun is restricted. The group that made last week’s trek in construction helmets and muddy shoes was a privileged minority, and all had particular reasons for being there.

Poet Homero Aridjis had come to excavate metaphors and philosophical meanings from the tunnel-cave, which he called “the matrix of the pyramid.”

“The art of Mexico is a difficult art because it is an art of stone,” he said. “Mexicans put the most abstract concepts into stone.”

Architect Karlos Zentero has been studying the use of drainage and rain-retention systems by the inhabitants of Teotihuacan. These might hint at ways for Mexico City to solve its chronic water-reclamation problems, said Zentero, who specializes in new housing construction.

Yet many of Teotihuacan’s most intriguing lessons are still studded with question marks. To this day, little is known about who founded the city, whose scale and splendor rivaled ancient Rome’s, according to scholars. Some inhabitants are thought to have been refugees fleeing a volcanic catastrophe in another part of the valley. Their language, the name of their settlement and what they called themselves remain mysteries.

But the city’s epic aspirations were writ large in its Wagnerian-scale architecture. Recent discoveries of jade and conch artifacts indicate that the people of Teotihuacan engaged in trade with areas as far away as the Gulf Coast and the Maya Empire in Guatemala.

The Aztecs, who came upon the site centuries after its glory had faded and its population dispersed, named it “the city where men become gods,” reasoning that only a race of super-beings could have built such a place. Eventually, the Aztecs appropriated Teotihuacan’s ruins, turning them into a kind of open-air sound stage for their own ornate rituals. Archeological research suggests that the Aztecs even converted some of the tunnels into living quarters. “Even in the beginning of the 20th century, we find people living in these tunnels,” Manzanilla says.

Last week’s visitors set off at 11 a.m., descending through a rough metal door hewn into the base of the roughly 210-foot pyramid. For archeologists, that door has been a bridge to Teotihuacan’s past, the men who ruled it and the terrifying gods who kept its citizens on their knees.

Discovered in 1971, the tunnel was probably formed out of lava spewing from one of the many volcanoes that tower over the Valley of Mexico, the 1 1/2-mile-high plateau across which present-day Mexico City sprawls. Those who subscribe to the natural cave theory believe that an underground spring once coursed through the tunnel, which terminated in a four-sectioned chamber resembling a cloverleaf that was later expanded and reconfigured by humans.

In the mid-1970s, art historian and Mesoamerican scholar Doris Heyden speculated that the tunnel’s first visitors might have been cultists who worshiped cave deities. The tunnel, she ventured, could even have been the mythical Chicomoztoc, or “Seven Caves” in the indigenous Nahuatl language. In Mesoamerica, Heyden wrote, Chicomoztoc “was, and still is, highly revered as the womb of the Earth, especially if there is a spring within it, inasmuch as life-giving water also springs from the maternal womb.”

But Heyden also thought that “Seven Caves” may have been less a real place than a mythical paradise, an archetype embedded in collective memory. “Every group, every individual, has his Chicomoztoc, his place of the ‘good old days,’ the place we would like to call home,” she wrote.

Manzanilla, who has surveyed the site with several geologists, insists that the chamber “cannot be a natural phenomenon.” Her theory is that the ancient inhabitants of Teotihuacan cut tunnels, including the one under the Pyramid of the Sun, out of volcanic slag and used the quarried material to build other structures in the city.

“Teotihuacan was a city built as a model of the Mesoamerican cosmos,” she says. “To become a sacred space it had to have an underworld, and the underworld was created with those tunnels.”

Manzanilla also sees significance in the four-petaled structure of the inner chamber, near the center of the pyramid. She has theorized that ancient Teotihuacan was ruled not by a single absolute monarch, like an Egyptian pharaoh, but by a group of perhaps two to four rulers (a practice common in central Mexico in the centuries after Teotihuacan’s decline). The number four recurs elsewhere in the design of Teotihuacan.

Unfortunately, Manzanilla says, when the tunnel under the Pyramid of the Sun was discovered, “there was no good archeological excavation to know what it was used for.” Though a few human bones were found in the tunnel, so far there has been nothing remotely comparable to the dozens of bodies of bound sacrificial victims or the exquisite jade statuettes recently unearthed in other parts of the city.

“This tunnel in particular, the most important one, we know nothing about it,” Manzanilla says.

Full body scan

That might change. Last week, as the visitors made their way toward the center of the Pyramid of the Sun, the low hum of machinery and the glare of electric bulbs signaled a new twist in the tunnel’s long, inscrutable history. Suddenly from out of the shadows near a small tent stepped a man in a white lab coat and a yellow plastic helmet, looking like a cross between a surgeon and a construction worker.

It was nuclear physicist Arturo Menchaca Rocha, who’s performing what amounts to a full body scan of one of the world’s bulkiest buildings. Last month, a team headed by Manzanilla and Menchaca, director of the Institute of Physics at the National Autonomous University of Mexico, began using what is reportedly the largest particle physics detector in Mexico to scan for variations in the density of the Pyramid of the Sun. The detector tracks the concentration of subatomic energy particles called muons, which are constantly passing from outer space into Earth’s atmosphere and interacting with matter.

Like an X-ray machine scanning a human patient, a particle detector can help uncover hidden things -- or an absence of them. An abnormal concentration of muons in a particular area of the Pyramid of the Sun, Menchaca says, may indicate the presence of a structural cavity that could be a chamber, a tunnel or a tomb. “Many Mexican pyramids are like Russian dolls, a pyramid inside a pyramid inside a pyramid,” Menchaca tells the visitors.

In the 1960s, Nobel laureate Luis Alvarez at UC Berkeley used muon scanning to prove there were no hidden chambers in Egypt’s great Khephren pyramid. If the $500,000 experiment at Teotihuacan is successful, it could open a new door into the mystery of what the ancients were really doing under the Pyramid of the Sun. “Maybe if we [find] a chamber, then we may use the chamber as a connecting device to find out what was inside the tunnels,” Manzanilla says.

There’s a certain poetic justice in Space Age technology being used to fill in the gaps of a city dedicated to cosmic harmony. Mysterious are the ways of the gods that watch over Teotihuacan.