Temoaya is a small city in the State of Mexico, accessible by public transport from Mexico City (western and northern bus terminals), Naucalpan (Toreo/Cuatro Caminos), as well as the state capital Toluca. From Naucalpan and Mexico City, it takes around 1 hour 40 minutes and MXN$62 or MXN$68.
The city itself has a nice central square, although nothing much beyond that.
The Otomi ceremonial centre is a site built based on the traditions of the Otomi people, and is a park these days with a small museum and space for grilling and stuff. Entry is MXN$30.
The bus or taxi colectivo between Temoaya and the ceremonial centre costs MXN$18 and goes every hour.
You can also eat there and there's a small artesian market.