The major buildings in the north half display a Toltec influence. Dominating them is El Castillo. The balustrade of the 91 stairs up each of the four sides is also decorated at its base by the head of a plumed, open-mouthed serpent. The interior ascent of 61 steep and narrow steps leading to a chamber is currently closed.
There is a ball court with grandstand and towering walls. El Castillo stands at the centre of the northern half of the site and almost at a right angle to its northern face runs the sacbé (sacred road) to the Cenote Sagrado (Well of Sacrifice). Into the Cenote Sagrado were thrown valuable propitiatory objects of all kinds, animal and human sacrifices. In 1962 the well was explored by an expedition, which recovered 4000 artefacts. To the east of El Castillo is the Templo de los Guerreros (Temple of the Warriors) with its famous reclining Chacmool statue. This pyramidal platform is closed off to avoid erosion.
Chichén Viejo (Old Chichén), where the Maya buildings of the earlier city are found, lies about 500 m by path from the main clearing. The famous El Caracol, or Observatory, is included in this group, as is the Casa de las Monjas (The Nunnery). A footpath to the right of the Casa de las Monjas leads to the Templo de los Tres Dinteles (Temple of the Three Lintels) after 30 minutes' walk. It requires at least one day to see the many pyramids, temples, ball courts and palaces, all of them adorned with astonishing sculptures. Excavation and renovation is still going on. Interesting birdlife and iguanas can also be seen around the ruins.