The Sun Dagger site is amazing. How'd they do that!
I found a video about it.
1 hour Video - 1999: The Mystery of Chaco Canyon
This documentary examines the ancient ruins of Chaco Canyon, built between 850 and 1150 A.D. in northwest New Mexico. This film describes and demonstrates the intricate and precise astronomical alignments among the many buildings spread over a wide desert area. These alignments, along with other evidence, support the theory that Chaco Canyon was a major ceremonial center.
You can watch this streaming video from here. Allow a few minutes to buffer. Very intriguing information and the alignments are very well illustrated.http://stagevu.com/search?for=chaco&in=Videos