The principal ruins cover an area of about 3 sq km (about 1 sq mi). The general structural type is that of the platform pyramid, ascended by means of broad stairways leading to vaulted chambers, the walls of which are covered with sculptured figures and hieroglyphic inscriptions or vividly colored paintings resembling the Aztec codices.
Each prominent structure is known by a distinct name, such as the Ball Court that was used for symbolic religious games. It is formed of two parallel walls, each 83 m (274 ft) long and 9 m (30 ft) thick, standing 36 m (120 ft) apart. Projecting from each wall 7 m (25 ft) above the ground is a sculptured ring of stone in the form of two entwined serpents. During the game the players attempted to send the ball through the ring.
Another important ruin is El Castillo, a large temple on a pyramidal mound 0.4 hectares (1.0 acre) in area and rising to a height of 30 m (100 ft), with staircases leading up on four sides to the temple of Kukulcan at the top. The Palace or Nunnery (Casa de las Monjas), the Sacred Well, the Temple of the Warriors, and the Caracol or Round Tower, probably an astronomical observatory, are among the other notable ruins.