Grave robbers had plundered this ancient Peruvian site for decades. But they missed one royal tomb, hidden for more than 1,000 years.

This story appears in the June 2014 issue of National Geographic magazine.

In the late afternoon light along the Peruvian coast, local workmen gather as archaeologists Miłosz Giersz and Roberto Pimentel Nita open a row of small sealed chambers near the entrance of an ancient tomb. Concealed for more than a thousand years under a layer of heavy adobe brick, the mini-chambers hold large ceramic jars, some bearing painted lizards, others displaying grinning human faces. As Giersz pries loose the brick from the final compartment, he grimaces. “It smells awful down here,” he splutters. He peers warily into a large undecorated pot. It’s full of decayed puparia, traces of flies once drawn to the pot’s contents. The archaeologist backs away and stands up, slapping a cloud of 1,200-year-old dust from his pants. In three years of digging at this site, called El Castillo de Huarmey, Giersz has encountered an unexpected ecosystem of death—from traces of insects that once fed on human flesh, to snakes that coiled and died in the bottoms of ceramic pots, to Africanized killer bees that swarmed out of subterranean chambers and attacked workers.

Plenty of people had warned Giersz that excavating in the rubble of El Castillo would be difficult, and almost certainly a waste of time and money. For at least a century looters had tunneled into the slopes of the massive hill, searching for tombs containing ancient skeletons decked out in gold and wrapped in some of the finest woven tapestries ever made. The serpent-shaped hill, located a four-hour drive north of Lima, looked like a cross between the surface of the moon and a landfill site—pitted with holes, littered with ancient human bones, and strewn with modern garbage and rags. The looters liked to toss away their clothing before they returned home for fear of bringing sickness from the dead to their families.

But Giersz, an affable 36-year-old maverick who teaches Andean archaeology at the University of Warsaw, was determined to dig there anyway. Something important had happened at El Castillo 1,200 years ago, Giersz was sure of that. Bits of textiles and broken pottery from Peru’s little-known Wari civilization, whose heartland lay far to the south, dotted the slopes. So Giersz and a small research team began imaging what lay underground with a magnetometer and taking aerial photos with a camera on a kite. The results revealed something that generations of grave robbers had missed: the faint outlines of buried walls running along a rocky southern spur. Giersz and a Polish-Peruvian team applied for permission to begin digging.

The faint outline turned out to be a massive maze of towers and high walls spread over the entire southern end of El Castillo. Once painted crimson red, the sprawling complex seemed to be a Wari temple dedicated to ancestor worship. As the team dug down beneath a layer of heavy trapezoidal bricks in the fall of 2012, they discovered something few Andean archaeologists ever expected to find: an unlooted royal tomb. Inside were interred four Wari queens or princesses, at least 54 other highborn individuals, and more than a thousand elite Wari goods, from huge gold ear ornaments to silver bowls and copper-alloy axes, all of the finest workmanship.

“This is one of the most important discoveries in recent years,” says Cecilia Pardo Grau, the curator of pre-Columbian art at the Art Museum of Lima. While Giersz and his team continue to excavate and explore the site, analysis of the finds is shedding new light on the Wari and their wealthy ruling class.

Emerging from obscurity in Peru’s Ayacucho Valley by the seventh century A.D., the Wari rose to glory long before the Inca, in a time of repeated drought and environmental crisis. They became master engineers, constructing aqueducts and complex canal systems to irrigate their terraced fields. Near the modern city of Ayacucho they founded a sprawling capital, known today as Huari. At its zenith Huari boasted a population of as many as 40,000 people—a city larger than Paris at the time, which had no more than 20,000 inhabitants. From this stronghold the Wari lords extended their domain hundreds of miles along the Andes and into the coastal deserts, forging what many archaeologists call the first empire in Andean South America.

Researchers have long puzzled over exactly how the Wari built and governed this vast, unruly realm, whether through conquest or persuasion or some combination of both. Unlike most imperial powers, the Wari had no system of writing and left no recorded narrative history. But the rich finds at El Castillo, a journey of some 500 miles from the Wari capital, are filling in many blanks.

The foreign invaders probably first appeared on this stretch of coast around the end of the eighth century. The region lay along what was then the southern frontier of the wealthy Moche lords, and it seems to have lacked strong local leaders. Just how the invaders launched their offensive is unclear, but an important ceremonial drinking cup discovered in El Castillo’s imperial tomb depicts poleax-wielding Wari warriors battling coastal defenders brandishing spear throwers. When the fog of war lifted, the Wari were in firm control. The new lord constructed a palace at the foot of El Castillo, and over time he and his successors began transforming the steep hill above into a towering temple devoted to ancestor worship.

Cloaked in nearly a thousand years of rubble and wind-borne sediment, El Castillo today looks like a huge stepped pyramid, a monument built from the bottom up. But from the beginning Giersz suspected that there was more to El Castillo than met the eye. To tease out the building plan, he invited a team of architecture experts to examine the newly exposed staircases and walls. Their studies revealed something that Giersz had suspected—that Wari engineers began construction along the very top of El Castillo, a natural rock formation, and eventually worked their way downward. They adapted this method from elsewhere, says Krzysztof Makowski, an archaeologist at the Pontifical Catholic University of Peru in Lima and the El Castillo project’s scientific adviser. “In the mountains the Wari made agricultural terraces, and they started at the top.” As they moved downward, they cut into the slopes to make a tier of platforms.

Along the summit of El Castillo the builders first carved out a subterranean chamber that became the imperial tomb. When it was ready for sealing, laborers poured in more than 30 tons of gravel and capped the entire chamber with a layer of heavy adobe bricks. Then they raised a mausoleum tower above, with crimson walls that could be seen for miles around. The Wari elite left rich offerings in small chambers inside, from the finely woven textiles that ancient Andean peoples valued more highly than gold; to knotted cords known as khipus, used for keeping track of imperial goods; to the body parts of the Andean condor, a bird closely associated with the Wari aristocracy. (Indeed, one title of the Wari emperor may well have been Mallku, an Andean word meaning “condor.”)

At the center of the tower was a room containing a throne. In later times looters reported to a German archaeologist that they found mummies arrayed in wall niches there. “We are pretty sure this room was used for the veneration of the ancestors,” says Giersz. It may even have been used for venerating the emperor’s mummy, yet to be discovered by the team.

To rub shoulders in death with members of the royal dynasty, nobles staked out places on the summit for mausoleums of their own. When they exhausted all the available space there, they engineered more, building stepped terraces all the way down the slopes of El Castillo and filling them with funerary towers and graves. So important was El Castillo to the Wari nobles, says Giersz, that they “used every possible local worker.” Dried mortar in many of the newly exposed walls bears human handprints, some left by children as young as 11 or 12 years old.

When the construction ended, likely sometime between A.D. 900 and 1000, an immense crimson necropolis loomed over the valley. Though inhabited by the dead, El Castillo conveyed a powerful political message to the living: The Wari invaders were now the rightful rulers. “If you want to take possession of the land,” says Makowski, “you have to show that your ancestors are inscribed on the landscape. That’s part of Andean logic.”

In a small walled chamber along the western slopes of the necropolis, Wiesław Więckowski hunches over a mummified human arm, brushing sand away from its gaunt fingers. For the better part of an hour now the University of Warsaw bioarchaeologist has been clearing this part of the chamber, collecting debris from a Wari funerary bundle and looking for the rest of the body. It’s slow, delicate work. As he edges his trowel into the corner of the room, he exposes part of a human femur lodged in a jagged hole in the wall. Więckowski frowns in disappointment. Looters, he explains, probably tried to haul the mummy out from an adjacent room and literally pulled it to pieces. “All we can say is that the mummy was a male person and quite old.”

A specialist in the study of human remains, Więckowski has begun analyzing the skeletons of all the individuals found in and near the imperial tomb. Preservation of human soft tissue in the sealed chamber was poor, Więckowski says, but his studies are starting to fill in key details of the lives and deaths of the highborn women and their guardians.

Almost all of those buried inside the chamber were women and girls who had likely died over a period of months, most probably of natural causes. The Wari treated them in death with great respect. Attendants dressed them in richly woven tunics and shawls, painted their faces with a sacred red pigment, and adorned them with precious jewelry, from gold ear flares to delicate crystal-beaded necklaces. Then mourners arranged their bodies in the flexed position favored by the Wari and wrapped each in a large cloth to form a funerary bundle.

Their social rank, says Więckowski, mattered as much in death as it did in life. Attendants placed the highest ranked women—perhaps queens or princesses—in three private side chambers in the tomb. The most important, a female of about 60, lay surrounded by rare luxuries, from multiple pairs of ear ornaments to a bronze ceremonial ax and a silver goblet. The archaeologists marveled at her wealth and conspicuous consumption. “This lady, what was she doing?” muses Makowski. “She was weaving with golden instruments, like a true queen.”

Beyond, in a large common area, attendants arranged the lesser noblewomen along the walls. Beside each, with few exceptions, they laid a container roughly the size and shape of a shoe box. Made of cut canes, it stored all the weaving tools needed to create high-quality cloth. Wari women were consummate weavers, producing tapestry-like cloth with yarn counts higher than those of the famous Flemish and Dutch weavers of the 16th century. The noblewomen buried at El Castillo were clearly dedicated to this art, creating textiles of the finest quality for the Wari elite.

When the chamber was ready for sealing, attendants brought the last offerings up the slopes of El Castillo: human sacrifices. There were six individuals in all, three children—including what might be a nine-year-old girl—and three young adults. It’s possible, says Więckowski, the victims were the offspring of the conquered nobility. “If you are the ruler and want people to prove their loyalty to the lineage, you take their children,” he says. When the killings were done, attendants threw the corpses into the tomb. Then they closed the chamber, placing the wrapped corpses of a young adult male in his prime and of an older woman at the entrance as guards. Each body had lost a left foot, perhaps ensuring that they couldn’t desert their posts.

Więckowski is awaiting the results of DNA analyses and isotopic tests to learn more about the females in the tomb and where they might have come from. But for Giersz the evidence is all beginning to add up to a detailed picture of the Wari invasion of the north coast. “The fact that they built an important temple here, on a prominent piece of land along the former borders of the Moche, strongly suggests that the Wari conquered the region and intended to stay.”

In a quiet back room at the Art Museum of Lima, El Castillo’s archaeologists beam as they examine some of the newly cleaned finds. For weeks now conservators have been stripping away the thick, black patina that coated many of the metal artifacts, revealing glimmering designs. Cushioned in tissue paper are three gold ear ornaments, each roughly the size of a doorknob and bearing the image of a winged deity or mythical being. Team member Patrycja Prządka-Giersz, a University of Warsaw archaeologist who is married to Giersz, looks them over in delight. These adornments, she says, “are all different, and we can only see them after conservation.”

Peering inside a large cardboard box on the table, Giersz finds one of the team’s prize discoveries: a ceramic pilgrim’s flask. Richly painted and decorated, the flask depicts a sumptuously dressed Wari lord voyaging by balsa raft across coastal waters teeming with whales and other sea creatures. Found among the cherished grave goods of a dead queen at El Castillo, the 1,200-year-old flask seems to portray an event—partly mythical, partly real—in the history of the north coast, the arrival of an important Wari lord, possibly even the Wari emperor himself. “And so we are starting to make a story of the Wari emperor who takes to the sea in a raft,” says Makowski with a smile, “an emperor who dies on the Huarmey coast accompanied by his wives.”

For now it is only a story, an educated archaeological guess. But Giersz, the maverick who saw the buried outlines of walls where others saw only looters’ rubble, still thinks that the tomb of a great Wari lord may lie somewhere in the maze of walls and subterranean chambers. And if the looters haven’t beaten him to the punch, he intends to find it.