The moderate, 1.5-hour hike to the Inca Granaries (Pinkuylluna) explores the Inca ruins that can be seen from town on the hillside opposite the Ollantaytambo fortress. The larger buildings were used for agricultural storehouses called colcas. Along with the multiple Inca sites, this steep hike offers great elevated views of Ollantaytambo [1] and the fortress.
To reach the trailhead from the plaza, take Calle Principal toward Cusco [2]. Take your first left after leaving the plaza completely on Calle Lares. After a few blocks, you will see a stone staircase on your right with a sign for Pinkuylluna.
The stone staircase continues up the mountain for 10 to 15 minutes before the trail forks. The trail to the right (with the wooden handrail) will lead you around the corner to the first Inca ruins.
After exploring these, the best option is to descend back down to the fork in the trail and take the trail uphill in the other direction. The trail passes another Inca site and arrives at the large four-tiered storehouse in about 20–30 minutes.
From here you can continue up the trail to the four towers that mark the crown of the head of the Tunupa, the god of abundance. If you continue up the mountain from here the views improve but the trail becomes unclear.
Links:
[1] http://www.moon.com/destinations/peru/the-sacred-valley/ollantaytambo
[2] http://www.moon.com/destinations/peru/cusco