Nazca Lines
BBC Online - The Lost City of Nasca, Nasca Lines, Nazca Lines, Nazca Lines and Ica Stones, Nazca Lines: Creation of a Full-Sized Duplicate, Project Nasca/Palpa, Promenade in Nazca, Skeptic's Dictionary: Nazca lines, Survive 2012: Nazca Lines, The Enigmatic Lines of the Nazca Pampa
The Ancient Walls: Enigma in the Andes
A slideshow of Andean archaeological sites by Richard Nisbet with a focus on Inca architecture and stonecutting. He suggests that the lower structure of Sacsahuaman is much older than c.1508.
World Mysteries: Sacsayhuaman
Describes several Inca sites in Peru, with some speculation about alternative dating.