<p>While the fractured stone was still in situ, archaeologists used laser-driven pulses of light to produce a green 3-D image of it. In an adjacent shaft lay six offerings of artifacts.</p>

While the fractured stone was still in situ, archaeologists used laser-driven pulses of light to produce a green 3-D image of it. In an adjacent shaft lay six offerings of artifacts.

Photograph by Guido Galvani and Maria Såanchez Vega, courtesy Mayor Project, National Institute of Anthropology And History, Mexico

Unburying the Aztec

The excavation of a sacred pyramid is turning up clues to the empire’s bloody rituals—but so far, no sign of its most feared emperor.

This story appears in the November 2010 issue of National Geographic magazine.

On the edge of Mexico City's famed Zócalo plaza, next to the ruins of the Aztec sacred pyramid known as the Templo Mayor, the remains of an animal—perhaps a dog or a wolf—were discovered. It had been dead for 500 years and lay in a stone-lined shaft eight feet deep. It is likely the animal had no name, nor an owner. Yet the anonymous canine had evidently meant something to someone. It wore a collar made of jade beads and turquoise plugs in its ears. From its ankles dangled bracelets with little bells of pure gold.

The archaeological team, led by Leonardo López Luján, unearthed the so-called Aristo-Canine in the summer of 2008, two years into an excavation that began when foundation work for a new building revealed an astonishing object. It was a 12-ton rectangular monolith made of pinkish andesite stone, broken into four large pieces, bearing the mesmerizingly horrific likeness of the earth goddess Tlaltecuhtli (pronounced tlal-TEK-tli)—the symbol of the Aztec life and death cycle, squatting to give birth while drinking her own blood, devouring her own creation. It was the third flat Aztec monolith to be discovered by accident in the vicinity of the Templo Mayor, along with a 24-ton black basalt Sun Stone (excavated in 1790) and an 8-ton Disk of Coyolxauhqui, the moon goddess (1978).

After years of painstaking excavation, López Luján and his crew have discovered, in a deep pit beside the monolith, some of the most exotic Aztec offerings ever found. Removing a stucco patch in the plaza floor, the excavators came upon 21 white flint sacrificial knives painted red: the teeth and gums of the Aztec earth monster, her mouth open wide to receive the dead. They dug deeper and found a bundle wrapped in agave leaves. It contained an assortment of sacrificial perforators made of jaguar bone, used by Aztec priests to spill their own blood as a gift to the gods. Alongside the perforators were bars of copal—priestly incense, another spiritual purifier. The perforators and incense were carefully arranged inside the bundle, along with feathers and jade beads.

To López Luján's surprise, several feet underneath this bundle lay a second offering, this one in a stone box. It held the skeletons of two golden eagles—symbols of the sun—with their bodies facing westward. Surrounding the eagles were 27 sacrificial knives, 24 of them dressed up in fur and other costumes, like raggedy puppets, to represent deities associated with the setting sun. By last January, the team had uncovered a total of six offerings in the shaft—the last one 24 feet below street level and containing a ceramic jar filled with 310 greenstone beads, earplugs, and figurines. The placement of every excavated object appeared to be governed by an exquisite logic, re-creating the Aztec Empire's entire cosmology.

It was at the very bottom of the second offering box that López Luján encountered the elaborately ornamented animal. Covering it were seashells and the remains of clams, crabs, and snails—creatures brought to this spot from the Gulf of Mexico, and the Atlantic and Pacific Oceans. In Aztec cosmology, López Luján knew, this tableau suggested the first level of the underworld, with the canine serving to guide its master's soul across a dangerous river.

But which human soul? Since the Spaniard Hernán Cortés's conquest of Mexico in 1521, no Aztec emperor's remains have been discovered. Yet historical records say that three Aztec rulers were cremated and their ashes buried at the foot of the Templo Mayor. When the Tlaltecuhtli monolith was found, López Luján noticed that the god depicted held a rabbit, with ten dots above it, in its clawed right foot. In the Aztec writing system, 10-Rabbit is 1502—the year, according to the codices surviving from the era, that the empire's most feared ruler, Ahuitzotl (pronounced ah-WEE-tzohtl), was laid to rest amid great ceremony.

López Luján is convinced that Ahuitzotl's burial place is somewhere near where the monolith was found. If he is right, then the Aristo-Canine may be a subterranean guide into the mystique of a people we know as the Aztec, but who called themselves Mexica (pronounced meh-SHEE-ka), and whose legacy forms the core of the Mexican identity. If López Luján finds Ahuitzotl's tomb, it will be the culmination of a remarkable 32-year inquiry into one of the most mythologized and misunderstood empires in the Western Hemisphere. Alas, little is certain when it comes to the Aztec Empire—a reign simultaneously brutal and complex, brief and literally paved over, yet manifestly prominent in a nation's consciousness a half millennium later.

"Past is present everywhere in Mexico," says López Luján. That is especially true of the Aztec Empire, virtually all of which resides just beneath the footsteps of a modern nation.

When word spread in 1978 that the Templo Mayor had been firmly located in the heart of the world's second most populous city, the resulting spectacle was more like a Broadway opening than an archaeological triumph. Jimmy Carter, François Mitterrand, Gabriel García Márquez, Jacques Cousteau, and Jane Fonda were among the dozens of celebrities who were treated to a tour of the dig site, some by Mexico's President José López Portillo, whose controversial decision to raze 13 buildings had made the excavation possible. And now it is happening again, with news circulating that one or more rulers may be entombed underneath the Zócalo's periphery. Today López Luján spends an inordinate amount of time chaperoning VIPs through the cramped and shrouded excavation site on the western edge of the pyramid. The Mexican press responds in droves to the latest archaeological revelations. Ordinary folks rap on the secure entrance to ask for a look; López Luján often obliges. The round-faced, good-humored, 46-year-old scholar understands the psychic pull. "Right now Mexicans realize they are living in a tragic present," he says. "But the past gives the people a way of saying they're somebody."

Unlike the Maya, Mesoamerica's other pre-Columbian powerhouse, the Aztec are exclusively identified with Mexico, and today it spares no opportunity to mythologize them. In the center of the Mexican flag is the Aztec eagle, which is also incorporated into the logos of the nation's two main airlines. There is Banco Azteca and TV Azteca, and the national soccer team wears uniforms featuring the iconic eagle and plays its home games in Estadio Azteca. And of course Mexico City itself—the nerve center of the nation—is an implicit homage to the city-state of Tenochtitlan and to Aztec indomitability.

But to see the Aztec in strictly iconic terms is to misunderstand them. To begin with, the mighty Aztec sustained their empire—the triple alliance of Tenochtitlan, Texcoco, and Tlacopan—for less than a century before it was eviscerated by European conquerors. For all the fear and loathing the rulers instilled in conquered regions, their dominion was ephemeral. They did not erect temples and disseminate cultural traditions across the countryside as the ancient Romans or Inca did. Instead, the Aztec maintained what some scholars call "a cheap empire," one in which the conquered were permitted to continue governing themselves so long as they ponied up tributary objects—a protection scheme buttressed by periodic shows of force. The Aztec chose to express their ingenuity largely in the epicenter of Tenochtitlan. Yet the great city was in many ways a repository of customs, images, and spiritual practices borrowed from previous civilizations. As López Luján's father, the Mesoamerican scholar Alfredo López Austin, puts it, "The most common misconception is that the Aztec were a completely original culture. They weren't."

But the harsh caricature of the Aztec as bloodthirsty is just as misguided. So grossly did the conquering Spaniards overstate the Mexica bloodlust—claiming, for example, that 80,400 humans were put to death at a single temple dedication, a feat that would have depopulated much of central Mexico—that some groups today feel justified in dismissing sacrifice as a European fiction. That's going too far. Chemical examinations during the past 15 years of porous surfaces throughout Mexico City reveal "blood traces everywhere," says López Luján. "You have the sacrificial stones, the sacrificial knives, the bodies of 127 victims—you can't deny the human sacrifice."

But, he is quick to add, you'll find human sacrifice everywhere in the world at that time. The Maya and numerous other cultures predated the Aztec's embrace of the practice. "It isn't the violence of a people but rather of an age—a warlike atmosphere when the religions of the time demanded that humans be sacrificed to replenish the gods," observes López Austin. And that spiritual imperative was received by the Aztec people with considerable anguish, according to analyses of codices by Harvard historian of religions Davíd Carrasco. "They were upset about sacrifice," he says. "I think there are a lot of signs that they were bothered by it."

The codices reveal that this was a people with a sophisticated awareness of the limitations of an empire that relied on human sacrifice. Even as they achieved their greatest might under Ahuitzotl, the predicate for their doom was being laid. A people who believed themselves at the center of a highly precarious universe were also inflicted with what Carrasco terms a "cosmic insecurity."

The empire began from scratch. The first Aztec, or Mexica, migrated from the north—from Aztlan, so it was said, though this ancestral homeland has never been located and perhaps existed only in legend. They spoke the Nahuatl tongue of the mighty Toltec, whose dominance across central Mexico had ended in the 12th century. But language was the Mexica's only connection to greatness. Chased off from one Basin of Mexico settlement after another, they at last happened upon an island in Lake Texcoco that no one else wanted and in 1325 proclaimed it Tenochtitlan. Little more than a swamp, Tenochtitlan lacked drinkable water and stones and wood for building. But its scruffy new inhabitants, though "almost totally uncultured," as renowned scholar Miguel León-Portilla puts it, compensated with what he terms "an indomitable will."

These settlers proceeded to dig through the ruins of the once great city-states of Teotihuacan and Tula. What they saw, they appropriated. By 1430 Tenochtitlan had become greater than either city, a marvel of landfill and aqueducts, divided by canals and causeways into four quadrants all in orbit around the centerpiece of a double-staircased pyramid with twin temples at its summit. None of their flourishes was particularly original, and that was the point. The Mexica sought to establish ancestral connections with empires past—particularly through the machinations of Tlacaelel, the royal consigliere who could boast that "none of the past kings has acted without my opinion or counsel." During the first half of the 15th century, Tlacaelel introduced a new version of Mexica history, asserting that his people were offspring of the great Toltec and elevating Huitzilopochtli—their patron god of the sun and of war—to the pantheon of exalted Toltec deities. The royal counselor went one step further. As Miguel León-Portilla writes, Tlacaelel crafted their imperial destiny as "the conquest of all other nations … to capture victims for sacrifice, because the source of all life, the sun, would die unless it were fed with human blood."

Thus did the reviled newcomers from the north ascend to nobility. They subjugated town after town in the Basin of Mexico. Under Moctezuma I, in the late 1440s, the Mexica and their allies marched over 200 miles to extend their empire southward into the present-day states of Morelos and Guerrero. By the 1450s they had pushed into the northern Gulf coast. And by 1465 the Chalco Confederacy, the lone holdout in the Basin of Mexico, was vanquished.

It would fall to the eighth Aztec ruler, Ahuitzotl, to stretch the empire to its breaking point.

He does not have a face. The man whose remains Leonardo López Luján hopes to find near the Templo Mayor is not represented in any artwork. "The only images we have of an Aztec ruler are of Moctezuma II, and these were made based on descriptions from the Spaniards after his death," López Luján says, referring to the last emperor who ruled over Mexico on the eve of the Spanish conquest. "About Moctezuma II, we have many details of his life. Of Ahuitzotl, we have very few."

Here's what we do know: The high-ranking military officer assumed the throne in 1486 after his brother Tizoc lost control of the empire and perished—perhaps by poison, perhaps by his younger brother's hand. His very name connoted violence; in Nahuatl parlance, the ahuitzotlwas a vicious otter-like being that could throttle humans with its muscular tail. Ahuitzotl's 45 conquests, the hallmark of his 16-year reign, were all colorfully memorialized in a Spanish viceroy's manuscript known as the Codex Mendoza. His armies conquered swaths along the Pacific coast, down into present-day Guatemala—and thus "expanded the empire's territorial reach to unprecedented limits," according to Carrasco. Some of these battles were purely exhibits of supremacy or to punish recalcitrant local leaders. The majority were to fulfill two bedrock lusts: tributary goods for Tenochtitlan and victims for the gods.

The first rule of Aztec dominion was well in place by the time Ahuitzotl acquired power: Take the conquered region's best stuff. "The merchants and traders played the roles of spies," explains Eduardo Matos Moctezuma, the archaeologist who oversaw the massive excavations at the Templo Mayor that began in 1978. Once they reported back about the resources a town possessed, the imperial forces would prepare their attack. "The military expansion was an economic expansion," says Matos Moctezuma. "The Aztec didn't impose their religion. They just wanted the products."

Not even gold held as much significance among the Mesoamerican peoples as jade, which represented fertility—and which in Central America could be found only in the mines of Guatemala. Unsurprisingly then, Ahuitzotl established trade routes into those lands—acquiring not only the metamorphic green stones but also, says López Luján, "quetzal feathers, gold, jaguar skins, and cacao, which was their money that grew on trees." With this abundance of riches, Tenochtitlan became a mercantile powerhouse as well as a cultural one—"the richest art center at that time, as Paris and New York would be later," says López Luján.

The Aztec bling became part of the ornately ritualized spirituality of Tenochtitlan. The Templo Mayor was not simply a burial pyramid like those erected by the ancient Egyptians but rather the symbol of the sacred mountain of Coatepec. The mountain was the site of a cosmological soap opera: The newly born sun god Huitzilopochtli slew his warrior sister, the moon goddess Coyolxauhqui, and flung her to the bottom of the mountain. With regular doses of such sacrificed warriors, the Mexica believed, the gods would be sated and the life cycle would go on. Without such sacrifices, the gods would perish and the world would end. "The sacred mountain is as important as the cross in Christianity," says Carrasco. For the Mexica, as for most Mesoamerican cultures, "there was this repetitive destruction and creation."

Paying homage to the sacred mountain meant marching colorfully garbed captive soldiers up the stairs of the pyramid, forcing them to perform ceremonial dances, and then cutting out their hearts and rolling their corpses down the steps. Rounding up the requisite prisoners to be sacrificed later was an ongoing campaign. Ritual battles were staged on specific days, on neutral land, with the explicit purpose of capturing prisoners, not territory. As the Aztec scholar Ross Hassig notes, each war "was formally initiated by burning a large pyre of paper and incense between the two armies." The Mexica did not speak of "holy wars," because for them there was no other kind. Combat and religion were inseparable.

In his very first campaign, Ahuitzotl led his army through several cities to the northeast to gather victims for his coronation rites in Tenochtitlan. Annoyed that several enemy lords failed to attend his crowning, the new ruler undertook a second series of invasions in 1487, pillaging the towns of the Huaxtec region and seizing an immense number of captives. Ahuitzotl's adversaries got the message. This time their leaders were well represented at the dedication of the Templo Mayor, and they watched in horrified amazement as the sacrificial victims they had surrendered were slaughtered in vast numbers by ritually ornamented priests.

Having instilled fear, Ahuitzotl would then display a lighter hand, plying visiting warlords with flowers and gifts and tobacco at his palace. The emperor enjoyed entertaining—"in his house the music never ceased, day or night," according to one text from the era—but his yen for lavish ceremonies, coupled with his many wives and children, took its toll on Tenochtitlan's budget. The list of tribute goods supplied by the conquered provinces and enumerated by the 16th-century friar and chronicler Diego Durán reads like ad copy for Tiffany & Co.: "gold, jewels, ornaments, fine feathers, precious stones … countless articles of clothing and many adornments." The banquets must have been sumptuous, with "an amazing quantity of cacao, chiles, pumpkin seeds, all kinds of fruit, fowls and game." But it was never enough. More conquests would be ordered, along with measures to demonstrate the empire's power—as when Ahuitzotl avenged the killings of several merchants in 1497 by ordering warriors into the offending villages to slay 2,000 for every dead merchant.

More than any ruler before him, Ahuitzotl expanded the empire's reach southward, sealed off trade from the powerful Tarascans to the west, and tightened the reins on all the subjugated territories. "He was more forceful, more brutal," says archaeologist Raúl Arana. "When people didn't want to pay tribute, he sent in the military. With Ahuitzotl, the Aztec went to the maximum expression of everything. And perhaps it was too much. All empires have a limit."

The Mexica people lost their great empire builder at the pinnacle of their dominance. In 1502—10-Rabbit—Ahuitzotl perished, supposedly from a blow to the head while escaping his palace during a flood. The flood was caused by a hastily built aqueduct project Ahuitzotl had initiated to harness the springs flowing out of neighboring Coyoacan. The town's ruler had warned Ahuitzotl about the spring's highly irregular flows. The emperor had responded by putting the ruler to death. At Ahuitzotl's funeral, 200 of his slaves were selected as his companions for the hereafter. Outfitted in fine garments and carrying provisions for the journey, the slaves were led to the Templo Mayor, where their hearts were torn out and their bodies cast onto a funeral pyre. Their remains, and those of their master, were said to be buried in front of the Templo Mayor.

That very spot is where the Tlaltecuhtli monolith and the Aristo-Canine were discovered. López Luján's team has excavated other offerings in the immediate vicinity. One was found underneath a Tuscan-style mansion built for one of Cortés's soldiers. Another was discovered several feet under the large stone slab. In both cases López Luján knew where to look by tracing a complicated series of east-west axes, or "imaginary lines," on a map of the site. "There's always this repetitive symmetry," says López Luján. "It was like an obsession with them."

The archaeological team's work is slow and unglamorous. Some of this is due to the challenges of any urban excavation: obtaining permits and circumnavigating sewer and subway lines; avoiding underground telephone, fiber optic, and electric cables; and maintaining security for an archaeological area that lies within one of the world's most alluring pedestrian zones. But as much as anything else, López Luján's crew labors painstakingly because the exactitude of the Aztec requires no less. Standing over a pit where, in May 2007, his team unearthed an offering box no bigger than a footlocker, he says, "It took 15 months for us to go through that entire offering. In that small space, it had ten layers and over 5,000 objects. The concentration, the richness, is incredible.

"It looks random, but it's not," López Luján continues. "Everything has a cosmic significance. The challenge for us is to discover the logic and the spatial distribution patterns. When Leopoldo Batres worked here [during the turn of the previous century], he was interested in the objects themselves. They were archaeological trophies to him. What we've discovered in the 32 years we've been working here is that the objects aren't so important by themselves but by their connection in space."

Every finding is a huge boon for Mexico since so many fine artifacts were seized by the conquistadores and brought back to Spain, where they have been dispersed throughout Europe. Beyond their aesthetic value, the new discoveries highlight the Aztec's attention to detail—a preoccupation owing to the high stakes involved. For the Aztec, the appeasement of the gods—and thus the world's survival—depended on an ever growing, ever demanding empire that ultimately could not be sustained. As Carrasco says, "The irony of empire is that you push to the periphery and you push too far, until you become the periphery. You're so far from home that you can't support your warriors with food and transport and you can't protect your merchants. The empire becomes too expensive. And the Aztec couldn't manage it."

Ten years before the Spaniards arrived, Ahuitzotl's successor, Moctezuma II, was apparently plagued by visions and portents. Despite having continued his predecessor's expansionist ways, despite his great power and his gold and turquoise diadem and his 19 children and his zoo crammed with exotic animals and "dwarfs and albinos and hunchbacks"—despite all of this, the ninth Aztec ruler was beset by his own cosmic insecurity. In 1509, according to one codex, "a bad omen appeared in the sky. It was like a flaming ear of corn … it seemed to bleed fire, drop by drop, like a wound in the sky."

Moctezuma's worries were justified. "There were more than 50,000 indigenous warriors revolting, wanting to keep their goods and wanting the Aztec attacks to stop in their community," says Carrasco. Absent this appetite for an uprising, the 500 Spaniards who docked at Veracruz in the spring of 1519, even with their guns and cannon and horses, would have been no match for the Aztec armies.

Instead, Cortés's contingent arrived in Tenochtitlan on the eighth of November escorted by thousands of Tlaxcalan and allied warriors. As awed as the Spaniards were by the spectacle of this gleaming city on a lake—"some of the soldiers even asked whether the things that we saw were not a dream," one eyewitness recalled—they were not daunted by their host's prowess. Rather, it was Moctezuma who seemed unsure of himself. According to Mesoamerican legend, the great bearded deity Quetzalcoatl—banished after committing incest with his sister—would one day return by water to restore his lordship. This notion was not lost on Moctezuma, who presented Cortés with "the treasure of Quetzalcoatl," a head-to-toe costuming topped off with "a serpent mask inlaid with turquoise."

But was Moctezuma really interpreting the Spaniard as the second coming of the feathered-serpent god, as has long been believed? Or was he cunningly outfitting Cortés in the godly garment of the soon-to-be sacrificed? The gesture was a final Aztec ambiguity. Thereafter, the facts are unassailable. The streets of Tenochtitlan ran red, and in 1521 an empire was buried.

"We're persuaded that sooner or later we'll find Ahuitzotl's tomb," says López Luján. "We're digging deeper and deeper." But no matter how deep the archaeologist digs, he will never unearth the core of the Aztec mystique. It will continue to occupy modern Mexico's psyche—there to be felt if not seen, at once primitive and majestic, summoning from ordinary mortals the power to turn swamps into kingdoms.

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