Zona Arqueológica de Plazuelas

Plazuelas spreads over some 34 hectares on the southern foothills of the Sierra de Pénjamo, next to the community of San Juan el Alto and about 11 km west of the town of Pénjamo. It is widely regarded as the most important archaeological site in Guanajuato. The city was built across three hillsides cut by two ravines: the eastern one, Agua Nacida, holds a spring that supplied the settlement, while the western one, Los Cuijes, only carries water in the rainy season. Visitors see the central hillside.

Its peak is dated to roughly AD 450 to 700, though other estimates place the occupation between 600 and 900. Either way, it ended burned and abandoned, though local people kept remembering it as a sacred place. Who built it is not known for certain. It is linked to the so-called Bajío tradition, a web of farming towns that traded between central, western and northern Mesoamerica, and its layout borrows features from distant places such as the Guachimontones of Teuchitlán in Jalisco.

The main building, Casas Tapadas, is a rectangular platform about 132 by 89 m carrying three aligned pyramid bases, a sunken patio of the kind typical of the Bajío, and a perimeter wall with a bench along its inner face and seven entrances. A 220 m causeway links it to the I-shaped ball court, roughly 65 by 31 m, where serpent sculptures were found at the four corners. The remains of a temazcal sweat bath lie to the west.

What sets Plazuelas apart is its carved stone: more than a thousand igneous boulders around the esplanade bear spirals, circles, lines and animal figures. The best known, La Maqueta, is a scale model of Casas Tapadas showing its stairways and entrances. Lightning, clouds, serpents and shells recur in the ornament and point to worship of water, earth, fire and wind, with the rain god Tláloc to the fore. The site museum holds sculpture, a stone phallus and turquoise jewelry with figures only 3 mm tall.