Via Quickbird, Masini and colleagues collected high-resolution infrared and multispectral images. After the researchers optimized the data with special algorithms, the result was a detailed visualization of a pyramid extending over a 97,000-square-foot (9,000-square-meter) area.
Cahuachi is the best-known site of the Nazca civilization, which flourished in Peru between the first century B.C. and the fifth century A.D. and slid into oblivion by the time the Inca Empire rose to dominate the Andes. Famous for carving in the Peruvian desert hundreds of geometric lines and images of animals and birds that are best viewed from the air, the Nazca people built Cahuachi as a ceremonial center, molding pyramids, temples and plazas from the desert itself. There, priests led ceremonies including human sacrifices, drawing people from across the region.
The discovery wasn't a surprise to archaeologists, since some 40 mounds at Cahuachi are believed to contain the remains of important structures. "We know that many buildings are still buried under Cahuachi's sands, but until now, it was almost impossible to exactly locate them and detect their shape from an aerial view," Masini said. "The biggest problem was the very low contrast between adobe, which is sun-dried earth, and the background subsoil."
The researchers investigated a test area along the river Nazca. Covered by plants and grass, it was about a mile away from Cahuachi's archaeological site, which contains the remains of what is believed to be the world's biggest mud city.