El Saucillo Aqueduct is Huichapan's standout sight: a stone aqueduct built between 1753 and 1758, with 14 arches and a maximum height of about 44 metres. It crosses a canyon with the kind of scale you do not expect from a small inland town.
The surrounding Bioparque El Saucillo adds hiking, mountain biking, rappelling, and other outdoor activities when operating, but the aqueduct itself is the reason to come. Walk down into the ravine if conditions allow; the arches look far more impressive from below than from the access road.