It's not that aqueducts aren't impressive, but I have much stronger memories of my conversation with my taxi driver on the way to and from the Aqueduct of Padre Tembleque Hydraulic System in January 2017 than I have of the actual aqueduct itself. After my visit, I'm still not sure exactly what it adds to the list. The Romans were constructing aqueducts with skill across Europe (see Segovia) many centuries before the technique was brought to the Western Hemisphere; I'd be more impressed with recognizing indigenous water management techniques. What constitutes the importance of this aqueduct to UNESCO, though, is the use of adobe, an adaptation of local building techniques, which enabled the construction of the picturesque span over the valley near Tepeyahualco. This main span is what draws most visitors, and it is the section I chose to visit. A sign near the parking area gave me some background about the route of the aqueduct, and a path allowed me to walk next to the tall arches. All told I didn't need much more than a half hour to visit this site; the remainder of my trip I spent in a fascinating but fretful conversation with my taxi driver, who used to live in the United States, about the future of Mexican immigration to the US after the presidential inauguration that week.

Logistics: The Aqueduct of Padre Tembleque requires private transporation, but can easily be paired with a visit to nearby Teotihuacan; I chose to hire a taxi to take me to the aqueduct in the morning and then drop me off at Teotihuacan to spend the remainder of the day.