Forty nine miles from Cusco lies a monumental architectural work whose fortifications were still under construction when the Spanish conquest started. At an altitude of 9,160 ft (2,792 m), the air is somewhat thin, but it is a comfortable descent from Cusco (11,152 ft, 3400 m).
There is both a thriving town and an impressive set of Inca ruins. In the town some of the buildings are sitting on Inca foundations and a few even sport Inca doorways. You can even find some of the best preserved examples of the kancha architectural design, a rectangular enclosure containing three or more rectangular buildings located around a central courtyard.
The ancient city was a complex of military, religious, administrative, and agricultural importance. The principal temple was partially destroyed in the conquest, but the perfectly fitted stone facade remains. Other buildings on the temple mount were under construction at the time, and large finely cut stones still lie where they were waiting to be lifted into place.
Some of the structures at this site date to the middle of the 15th century during the reign of Pachacuti Yupanqui (1438-1471), but the city was not fortified at that time. The fortifications were added hastily at the time of the Spanish invasion and do not represent the kind of sophisticated stonework seen in Cusco or Machu Picchu. The stonework on the temple mount, though, includes some of the finest in the empire.
The Eastern face of the temple mount shows unusually large terraces with walls reaching a height found only in sites of extremely high status. If you look closely at the image you can also see storage facilities built into the rock face to the right of the terraces.
From the top of the temple mount, you can get a great view of the surrounding valley. If you look carefully, you can even see large stones that were in transit from the opposite side of the valley at the time the Spanish arrived. The ramp used to lift the stones onto the temple mount is still intact.
The type of stone found in the majority of the constructions at Ollantaytambo came from a quarry near the bottom of a mountain on the opposite side of the valley. The 13 minute video below (in Spanish) shows the quarry and the explains the process of production.
The largest stones came from a second quarry much further up the same mountain.