Road engineers could hardly believe their eyes when they visited the Colca Valley in the late 1970s to build the area’s first road.

Condors cruised through the brilliant blue skies. A river lay thousands of feet below at the bottom of an impenetrable canyon. Potatoes and corn overflowed from thousands of stone terraces.

Stone-and-adobe villages, each with a small but elegant colonial church, were strung like pearls along the valley rim. Women herded alpacas while dressed in fantastically embroidered skirts and hats with ribbons and sequins.

Even with a spate of new roads and tourist hotels, Colca Valley and Canyon are still an odd combination of historical time warp and geological anomaly. The Collagua and Cabana peoples who lived here for at least 2,000 years, from 800 B.C. onward, built an ingenious terracing system on the valley walls that collects snowmelt from nearby volcanoes.

Inca Mayta Cápac arrived here with his army in the 15th century and, according to Spanish chronicler Francisco Jerónimo de Oré, sealed the conquest by marrying Mama Tancaray Yacchi, daughter of a local Collagua chief. The Inca built for her a house of copper that, according to legend, was melted to make the gigantic bells that still hang in Coporaque’s towers.

The Spaniards, a century after the Incas, were less kind: They herded villagers into reducciones (new settlements) and put them to work in plantations or the nearby Caylloma silver mine. All the while, the Collaguas absorbed Catholic imagery into their festivals. The women copied the petticoats of the Spanish women, adding their natural indigos and bright blues and their fine, paisleylike embroidery. And then Colca, with neither roads nor communications, was forgotten.

In 1979, shortly after the road was built for the Condorama Dam, a motley crew of six Polish adventurers led by Piotr Chmielinski and Andrzej Pietowski, with Peruvian Antonio Vellutino (the owner of Cusipata), discovered another side of Colca: adventure. They made the first river descent of the Colca Canyon. In a grueling five-week journey, they navigated the Class V waters of the canyon and confirmed that the Colca Canyon was at least 3,400 meters deep—more than twice the depth of Arizona’s Grand Canyon. Since that expedition, Colca Canyon has become, along with Cusco and Huaraz, a center for adventure sports.

From Cabanaconde, near the end of the canyon road, climbers begin to climb Ampato, the 6,300-meter volcano where the Juanita mummy was discovered. Numerous other hikes and mountain-bike routes lead throughout the canyon and its spectacular villages.