Update, March 2015
I reached the town of Chlchihuites via bus from Sombrerte. The following day I hired a taxi to take me to Alta Vista Ruin Site, a long downhill glide from Chalchihuites. I was soon in the small museum looking over the ceramic objects and site scale models.
The caretaker approached and greeted me, the only visitor. He explained that the site had the same name carried by the nearby town but was more commonly called Alta Vista, the official name given it by the Government.
The caretaker told me that researchers at Alta Vista had found solar significance in the construction of the buildings situated on a gently sloping hillside at 7, 200 feet above sea level. The researchers cite deliberate placement by the builders of the ritual center at latitude 23* 28' 58", smack on the Tropic of Cancer, give or take a mile. The tropic line moves a few feet each year, I would learn, so the builders in ancient times could be forgiven their GPS and computer-less error.
City of Zacatecas
What they had built though was an ideal spot for the observation of the summer solstice or zenith day. At that location the sun would appear to stand still in its movement north over the earth on June 21 and would not only linger for a day directly overhead at Chalchihuites, but appear to reverse direction and start its (apparent) annual movement south.
As I toured with the caretaker, he pointed out peaks in the distant hills where stone markers indicate a use of the center by builders of Teotihuacan to track the movements of the sun.
The site was occupied from 100 AD to 1400 AD but was in active building stages between 400 and 850 AD, this according to archaeological researchers. Some suggest that the Teotihuacan culture built the complex as a ritual center in the 4th century AD.
Archaeological investigation of the site began with the work of Mexican archaeologists Manuel Gamino who first explored the site in 1908. Later in 1971, Charles Kelley began digs at Alta Vista that spanned five years. His studies of the site and region continued for 45 years.
Archaeoastronomer Anthony F. Aveni of Colgate University, famed for his work with sun and star alignments on many Mexican sites, wrote, along with Kelly, in 1977 about the ruin and its solar significance in the alignment of walls and sight lines to the rising of the sun over distant mountains.
Aveni, Anthony, F. Horst Hartung, and J. Charles Kelley. 1982. "Alta Vista (Chalchihuites): Astronomical Implications of a Mesoamerican Ceremonial Outpost at the Tropic of Cancer." American Antiquity, vol. 47, pp. 316-335.
Zacatecas Zip line, hiking Tour
The caretaker didn't remember me from past visits as he pointed out features include a solar equinox alignment and a summer solstice alignment of the sun over the mountain peak, Picacho, in the distance to the southwest, and to ridge called Chapin at dawn, where investigators found two cross-shaped petroglyphs similar to ones used by the builders of Teotihuacan when they designed that city. Those markers at Chapin Mesa were the telling link between Alta Vista and its use by the distant City of Teotihuacan as a ceremonial outpost at the northern limit of Mesoamerica.
It became evident that the caretaker was out to prove all of this to me as he had me squatting and sighting along walls this way and that. He had many quirky facts to tell but I was relieved that he didn't pull out of his bag of tricks the lost tribe of Israel as a guide had done to Lorraine and me when we visited Monte Alban in Oaxaca.
Alta Vista Chalchihuites, Zacatecas