Pyramid of Tenayuca

19.5283°N, 99.1819°W.

The Pyramid of Tenayuca in the modern town of Tlalnepantla de Baz, just north of Mexico City, is the best-preserved example of the twin-stair pyramid that the Aztec inherited from the earlier Chichimec inhabitants of the Valley of Mexico. The pyramid was built and rebuilt in at least seven superimposed phases between approximately 1200 and 1500 CE, each phase encasing the previous structure in a larger envelope. The visible structure rises 19 metres in stepped tiers, with twin staircases on its western face leading to two summit shrines — the standard plan that the Templo Mayor at Tenochtitlan would replicate at vastly greater scale. The pyramid is encircled at its base by a coatepantli ("serpent wall") of 138 carved stone serpents. The pyramid was excavated by Ignacio Marquina and José Reygadas Vértiz for INAH in the 1920s and 1930s.

The Pyramid of Tenayuca is the prototype of the twin-temple plan, ringed by a wall of one hundred and thirty-eight stone snakes.