51km/32mi south-west of Sombrerete is the little township of Chalchihuites (Náhuatl: "chalchihuitl = "green stone") and from there it is another 7km/4.3mi to the extensive archaeological site of Chalchihuites, which is also known by the name Alta Vista. Very little is known about the people who built the site, which stretches across the
haciendas of Alta Vista, El Vergel and El Chapín. It was already settled at the time of Christ, although the heyday of the site would probably have been between the 5th and 7th c. It was not until the 11th c. that the town declined in importance and it is thought that it was abandoned about 1400. The location of the site, directly on the Tropic of Cancer, appears to have been due to astronomical calculations. It attained far-reaching importance both as a cult centre and as a trading-place in a mining region where dealings were conducted in flint, jade and turquoise.
The Ruins
This level site has an unwalled pathway which, from its position and construction, must have been used as an observatory. Next to it there is a curving snake-like wall with appropriate markings, the Hall of Columns (Salón de las Columnas) with 28 pillars and priest-alcoves with sacrificial and fire altars. Symbols of crosses carved into the rocks of Cerro El Chapín were, like almost all the buildings, created according to astronomical rules.