At the northern end of sacred valley,Ollantaytambo is rare if not unique in Peru.Ollantaytambo is a massive citadel located 50km from Machu Pichu.The citadel served as both a temple and a fortress.At some time unknown,and for reasons unknown, work mysteriously stopped on the huge project.(By unknown reason we haven't visit the so called huge project but from some of my photo you can see on the mountain the huge megalithic wall)