Adjacent to the great ballcourt is the tzompantli, a rack where the skulls of warriors, captives, sacrificial victims, and the winners of the games were displayed. The skulls were strung together through the sides, like that of barbequed meat.
Beyond the tzompantli are two platforms, the Platforms of the Eagles and Jaguars, and the Platform of Venus, dedicated to the planet that figured so much in Mayan astronomy. Beyond it was the Sacred Cenote, the water-filled sinkhole that became a pilgrimage site for the Mayans. Archaeologists recovered human remains, gold and other offerings from the bottom of the cenote. It's not as big as the one in Hacienda Lorenzo Oxman though.
On the east side of El Castillo is another stepped pyramid called Temple of the Warriors. On the top of the pyramid is a chacmool, a sculpture depicting a reclining human figure. On the figure's stomach is a bowl where human hearts are deposited during the ritual sacrifices.