Temple of Kukulkan

The Temple of Kukulkan, also called the El Castillo or the Castle, is the Mayan pyramid and temple in Chichén Itzá, in Yukatán, Mexico. It plays a major part in Changes.

Description
The Red King does his sacrificial rituals here.

The Temple of Kukulkan, the Feathered Serpent God, is the largest and most important ceremonial structure at Chichén Itzá. The ninety-foot tall pyramid was built between the 11th to 13th centuries directly upon the multiple foundations of previous temples. Each face of the four-sided structure has a stairway with ninety-one steps, which together with the shared step of the platform at the top, add up to 365. The pyramid is oriented to mark the solstices and equinoxes. At the base of the northern stairway, a doorway leads to an interior staircase ending at a small, mysterious shrine.

Changes
Harry was first led to and up the pyramid to the temple on top by Alamaya the priestess of Kukulkan to talk to the Red King. Harry promises to kill Arianna Ortega for him and he'll take his daughter in peace, if not, he's prepared to fight. They make a deal. While there alone, Harry had Bob identify how the bloodline curse is set up. Then he promised Maggie that he would take her away from the bad people.

After the duel and the ensuing fight at the Ball Court, Harry returned to the temple to save his daughter, but is stopped by the Red King and four Lords of Outer Night by freezing him in a will-lock. Using Amoracchius under a veil, Susan cuts off the Red King's knife-weilding arm just before he kills her daughter. Martin enters, betrays and captures Susan. Martin revealed that Harry is Ebenezar McCoy's grandson and that bloodline curse to be used with Maggie was intended to target Ebenezar as much as Harry. He told Susan that he was the one to tell the Reds abut Maggie. Susan attacks Martin, draining him. While Martin was dying he soulgazed Harry revealing that this was his real plan to destroy the Red Court. Harry breaks loose of their hold with Lea's aid and attacks the Red King. His screams of pain and fear call forth his forces. At her plea, Harry killed Susan—the youngest vampire—on the alter, releasing the bloodline curse and killing the entire Red Court.