Those ruins are ancient Inca houses in the Machu Picchu. During Inca times, more than 5000 people lived in this isolated and sacred city !
Also very sacred was the "Winay Picchu", the famous peak towering above the city, which can be seen clouded in the background of the photo. Climbing on the top is not very difficult, but beware the effects of vertigo...

Date: Tuesday, December 13 2005
Camera: NIKON D70
Focal length: 18 mm
Aperture: f/5.6
Exposure Time: 1/640 sec
Flash: Not Fired