From a Stanford University web site, which has many detailed diagrams of the site:
"Wiñay Wayna is an Inca site, neighbor to Machu Picchu, on an elevated perch overlooking the Urubamba River. It was discovered by the Wenner Gren Scientific Expedition to Hispanic America, which investigated both archaeological sites and native Andean peoples in 1940-42. Paul Fejos and his team documented a number of sites on or near one of the Inca roads leading toward Machu Picchu, a road now known as the "Inca Trail" by the thousands of trekkers who pass across it annually. The name Wiñay Wayna was subsequently given to the ruin by the eminent Peruvian archaeologist, Dr. Julio C. Tello, which Fejos reports as meaning "Eternal Youth."
The ruins consist of upper and lower house clusters, interconnected by a long, precipitous staircase with accompanying fountain structures, often referred to as "baths." A large area of presumably agricultural terraces lies just north of the house-staircase complex. The site is not unusual for those in this region: compact formations of architecture that conform to, and often take advantage of the local topography. The stonework is variable in quality, but significant portions are of high quality cut stone assembly. The site's lookout nature, its positioning near the important Inca access road, and the investment represented by it's architecture suggests it a place of some importance during the Inca occupation of this segment of the Urubamba drainage."
(click to enlarge) Winay Wayna seen from across a large valley, perhaps 1/2 mile away. The site is big!
(click to enlarge) The classic view from the top after climbing about 400 steps.
(click to enlarge) Close-up of one of the terraces