SALTA, Argentina — The maiden, the boy, the girl of lightning: they were three Inca children, entombed on a bleak and frigid mountaintop 500 years ago as a religious sacrifice.

Unearthed in 1999 from the 22,000-foot summit of Mount Llullaillaco, a volcano 300 miles west of here near the Chilean border, their frozen bodies were among the best preserved mummies ever found, with internal organs intact, blood still present in the heart and lungs, and skin and facial features mostly unscathed. No special effort had been made to preserve them. The cold and the dry, thin air did all the work. They froze to death as they slept, and 500 years later still looked like sleeping children, not mummies.

In the eight years since their discovery, the mummies, known here simply as Los Niños or “the children,” have been photographed, X-rayed, CT scanned and biopsied for DNA. The cloth, pottery and figurines buried with them have been meticulously thawed and preserved. But the bodies themselves were kept in freezers and never shown to the public — until last week, when La Doncella, the maiden, a 15-year-old girl, was exhibited for the first time, at the Museum of High Altitude Archaeology, which was created in Salta expressly to display them.

The new and the old are at home in Salta. The museum faces a historic plaza where a mirrored bank reflects a century-old basilica with a sign warning churchgoers not to use the holy water for witchcraft. Now a city of 500,000 and the provincial capital, Salta was part of the Inca empire until the 1500s, when it was invaded by the Spanish conquistadors.