Inca mountain city discovered in Peru in 1911 (5,6)
I believe the answer is:
machu picchu
(Other definitions for machu picchu that I've seen before include "peak" , "Old Inca settlement, now a major Peruvian tourist destination" , "Inca mountain city" , "Famous Inca city" , "Inca fortress city in the Peruvian Andes" .)