For the handful of people who pursue it, high-altitude archaeology is not only a career but a calling. Constanza Ceruti is one of the few scientists, and the world's only woman, to choose the challenging field. As she explained, "Few mountain climbers will be happy to spend a month working at the top after reaching a summit. On the other hand, most archaeologists will not enjoy the harsh climbing conditions. You have to like both mountaineering and archaeology very much to commit to this work."

For Ceruti, the calling came early. At ten she was keenly interested in anthropology, ancient religions, and nature. By 14 she knew high-altitude archaeology in her native Argentina was the perfect way to combine those passions. A degree in anthropology from the University of Buenos Aires followed, then a Ph.D. in history from the University of Cuyo in Mendoza.

Now a professor at Catholic University in Salta, Argentina, Ceruti specializes in exploring and excavating Inca Empire ceremonial centers on the summits of sacred Andean mountains.

She has climbed and performed archaeological research on more than a hundred mountains above 16,500 feet. Just to reach the bases of distant peaks, she has endured lightning storms, blizzards, gale winds, low oxygen levels, frostbite, and 60-mile hikes.

Unfazed, she notes, "Just think of the Incas who made these ascents 400 years before the advent of modern mountaineering. They looked for the slope offering the easiest route up. That still makes sense today and improves my chance of encountering traces of their presence."

Mountaintop worship sites are not found in other ancient cultures, a fact that has political as well as religious explanations. As the Inca expanded their empire, designating summits as sacred served to mark new territory as their own.

Perhaps Ceruti's most impressive find took place on the 22,100-foot summit of Llullaillaco Volcano, where the expedition she co-led unearthed the three best preserved mummies ever discovered. With hair still visible on arms, the mummies looked as if they had just been buried rather than frozen for 500 years. Elaborate gold and silver statues, ornate textiles, even pottery still containing food were also excavated.

The team braved driving snow and 70-mile-an-hour winds to complete their work, but for Ceruti the conditions posed no deterrent. "When we found the mummies, I remember a profound silence falling over the group. It is so humbling to look into the eyes of another human being from half a millennium ago."

"These mountains are so remote," she says. "Not only am I often the first archaeologist on the site but the first modern person to arrive since the Incas. It's amazing to enter a sacred place where I know the last human footsteps were those of Inca priests."

Interpretation of Ceruti's finds takes place back in the laboratory. "No one ever witnessed a mountaintop ceremony," she says. "So to bring these tangible remains alive again takes a lot of detective work. Why were some mountains considered sacred and others not? Why did some sites have simple shrines while others contained much more complicated ceremonial complexes? By considering archaeological evidence, historical sources from the time of the Spanish conquest, and traditional beliefs that still exist, we can reconstruct what these ancient sites looked like, the symbolic meaning behind each artifact, and how ceremonies took place.

"With this cultural and historical context," she says, "we can better explain things that happen today and help ensure these important areas will be protected. Some have already been destroyed by looters, so our work is very urgent. Finding and preserving these unique sites before they are destroyed allows me to give something back to the mountains. For me, studying these sacred summits is a life commitment. There's something about being up here that is phenomenal scientifically, culturally, and spiritually."