Acueducto del Padre Tembleque

The Padre Tembleque aqueduct is the most ambitious water project of 16th-century New Spain, and the main reason Zempoala is on the UNESCO World Heritage list. It was planned by Francisco de Tembleque, a Franciscan friar from Toledo who saw how scarce water was on these high plains. Working with the indigenous towns of the area through the 1550s and 1560s, he brought water from springs at the foot of Cerro Tecajete to Otumba, with a branch serving Zempoala.

The system runs about 48 kilometers, and around 95 percent of it is an underground channel. What visitors come to see is the Arquería Mayor near Santiago Tepeyahualco, on the Hidalgo–State of Mexico line: 68 round arches stretching for close to a kilometer over the Papalote ravine, reaching nearly 39 meters at the tallest arch. It mixes Roman, Moorish and Mesoamerican building traditions; the arches were raised over adobe forms, a local technique, and the west face carries dozens of painted and carved indigenous glyphs.

UNESCO listed the hydraulic system in 2015. Come in the late afternoon, when the low sun lights up the stone.