John NOBLE-WILFORD, A "Lost City" of the Incas Begins to Reveal Its Secrets. [The New York Times, march 30 and march 31, 2003]. Working with new evidence and a trove of re-examined relics, many of them recovered from the basement of a Yale museum here, archaeologists have revised their thinking about the significance of Machu Picchu, the most famous "lost city" of the Incas. The new interpretation comes more than 90 years after the explorer Hiram Bingham III made his way to a hïgh ridge in the Andes of Peru and beheld a dreamscape out of the pre-Columbian past. There was Machu Picchu, the imperial stones that have entranced and mystified visitors and scholars alike. The expression "lost city," popularized by Bingham, was the magical elixir for rundown imaginations. The words evoked the romanticism of exploration and archaeology at the time, in the summer of 1911. But finding Machu Picchu proved to be easier than solving the mystery of its place in the Inca empire, arguably the richest and most powerful in the New World when Europeans arrived. The imposing architecture attested to the skill and audacity of the Incas. But who had lived at this isolated site and for what purpose? Bingham, a historian at Yale, advanced three hypotheses - all of them dead wrong. A revival in research in recent years, experts say, has solved the mystery and, to a large degree, demystified Machu Picchu. The spectacular site was not, as Bingham supposed, the traditional birthplace of the Inca people or the final stronghold of the Incas in their losing struggle against Spanish conquest in the 16th century. Nor was it a sacred spiritual center occupied by chosen women, the "virgins of the sun," and presided over by priests who worshiped the sun god. Instead, Machu Picchu was one of many private estates of the emperor and, in particular, the favored country retreat for the royal family and Inca nobility. This interpretation and other new research inform a major exhibition at the Peabody Museum of Natural History at Yale. The show is called "Machu Picchu: Unveiling the Mystery of the Incas". Dr- Richard L- Burger, the director of the Peabody and a specialist in Inca archaeology, said the show, the largest on the Incas ever assembled in the United States, would "change the way people see Machu Picchu". Dr- Burger and Dr- Lucy C- Salazar, also an archaeologist, are co-curators of the exhibit. The new interpretation, generally supported by other experts, is based largely on a study of 16th-century Spanish legal documents and a more detailed analysis of pottery, jewelry, tools, skeletal remains and other material found in the ruins. Although the site has long been Peru's most popular tourist draw, the haunting shells of temples, palaces and other structures had ceased to attract many archaeologists. Bingham's long shadow may also have discouraged research. In his three expeditions to Machu Picchu from 1911 to 1915, he established himself as the "discoverer" and foremost interpreter of the lost city. His 1930 book, "Machu Picchu: A Citadel of the Incas," endured as the definitive treatise on the site. But he was untrained in archaeology. Archaeologists today have destroyed Bingham's theories. For example, Dr- Salazar's exhaustive examination of pottery contradicted Bingham's speculation that Machu Picchu was somehow associated with the earliest Incas. All the pottery styles were 15th century. That and other evidence suggest that construction on the site began around 1450. That was in the reign of Pachacuti, considered the Alexander the Great of the Incas. In archives at Cuzco, the former Inca capital, Dr- John Howland Rowe, an anthropologist at the University of California at Berkeley, found a 16th-century lawsuit filed by Pachacüti' descendants. They sought the return of family lands, including a retreat called Picchu. That sent Dr- Burger, a onetime student of Dr- Rowe, and Dr- Salazar back to Machu Picchu. "We then felt this was a royal estate, a country palace," Dr- Burger recalled. "All Machu Picchu is a. big palace". Whatever Pachacuti, empire builder, had in mind, Dr- Salazar said, Machu Picchu, at an elevation of 6750 feet, "shows what the New World had achieved before the Spanish arrived". Some of the engineering and architecture was better than in Seville, she noted, and the Spanish "could not believe how people, people without writing, could have built something like this".