The Mayan city in Mexico that features the Pyramid of Kukulcán and is a World Heritage Site is Chichen Itza.
Chichen Itza was one of the most important Maya cities in the northern Yucatán Peninsula. Its central monument, El Castillo, is also called the Temple or Pyramid of Kukulcán, after the feathered-serpent deity associated with the Maya. The pyramid dominates the site’s Great North Platform.
The city combines Maya building traditions with influences from central Mexico, especially in its monumental sculpture, temples, ball court, and ceremonial architecture. At the spring and autumn equinoxes, sunlight creates a serpent-like pattern along the pyramid’s northern staircase, a visual effect linked to Kukulcán.
UNESCO inscribed the Pre-Hispanic City of Chichen-Itza as a World Heritage Site in 1988. Uxmal and Palenque are also major Maya sites in Mexico, while Tikal is in Guatemala. The name is often written Chichén Itzá, but “Chichen Itza” is the same place and is a fair answer.