El Castillo (, 'the Castle'), also known as the Temple of Kukulcan, is a Mesoamerican step-pyramid that dominates the center of the Chichen Itza archaeological site in the Mexican state of Yucatán. The temple building is more formally designated by archaeologists as Chichen Itza Structure 5B18.
Structure
Built by the pre-Columbian Maya civilization sometime between the 8th and 12th centuries CE, the building served as a temple to the deity Kukulcán, the Yucatec Maya Feathered Serpent deity closely related to Quetzalcoatl, a deity known to the Aztecs and other central Mexican cultures of the Postclassic period. It has a substructure that likely was constructed several centuries earlier for the same purpose.
The temple consists of a series of square terraces with stairways up each of the four sides to the temple on top. Sculptures of plumed serpents run down the sides of the northern balustrade. Around the spring and autumn equinoxes, the late afternoon sun strikes off the northwest corner of the temple and casts a series of triangular shadows against the northwest balustrade, creating the illusion of the feathered serpent "crawling" down the temple. To contemporary visitors, the event has been very popular and is witnessed by thousands at the spring equinox, but it is not known whether the phenomenon is a result of a purposeful design since the light-and-shadow effect can be observed without major changes during several weeks near the equinoxes.
Scientific research led since 1998 suggests that the temple mimics the chirping sound of the quetzal bird when humans clap their hands around it. The researchers argue that this phenomenon is not accidental, that the builders of this temple felt divinely rewarded by the echoing effect of this structure. Technically, the clapping noise rings out and scatters against the temple's high and narrow limestone steps, producing a chirp-like tone that declines in frequency.
All four sides of the temple have approximately 91 steps which, when added together and including the temple platform on top as the final "step", may produce a total of 365 steps (the steps on the south side of the temple are eroded). That number is equal to the number of days of the Haabʼ year and likely is significantly related to rituals.
The structure is high, plus an additional for the temple at the top. The square base measures across.
Construction
The construction of the Temple of Kukulcán ("El Castillo"), like other Mesoamerican temples, likely reflected the common practice by the Maya of executing several phases of construction for their temples. The last construction probably took place between 900–1000 CE, while the substructure may have been constructed earlier, between 600–800 CE. Based on archaeological research, construction of the Temple of Kukulcán was based on the concept of axis mundi. Anthropologists think that the site remained sacred regardless of how the structure was positioned on the location. When a temple structure was renewed, the former construction was destroyed using a ritual that involved resolving the space of spiritual forces to preserve its sacredness. Additionally, the color red appears to have been significant to Maya cultural symbolism. It is associated with creating life as well as death and sacrifice. An approximate correspondence with the Sun's positions on its zenith and nadir passages is likely coincidental, however, because very few Mesoamerican orientations match these events and even for such cases, different explanations are much more likely. Since the sunrise and sunset dates recorded by solar orientations that prevail in Mesoamerican architecture, tend to be separated by multiples of 13 and 20 days (i.e. of basic periods of the calendrical system), and given their clustering in certain seasons of the year, it has been argued that the orientations allowed the use of observational calendars intended to facilitate a proper scheduling of agricultural and related ritual activities. In agreement with this pattern, detected both in the Maya Lowlands and elsewhere in Mesoamerica, the north (and main) face of the temple of Kukulcán at Chichén Itzá has an azimuth of 111.72°, corresponding to sunsets on May 20 and July 24, separated by 65 and 300 days (multiples of 13 and 20). Significantly, the same dates are recorded by a similar temple at Tulum.
Recent developments
Around 2006, the National Institute of Anthropology and History (INAH), which manages the archaeological site of Chichen Itza, started closing monuments to the public. While visitors may walk around them, they may no longer climb them or enter the chambers. This followed a climber falling to her death.
Researchers discovered an enormous cenote (also known as a sinkhole) beneath the 1,000-year-old temple of Kukulcán. The forming sinkhole beneath the temple is approximately and as many as deep. The water filling the cavern is thought to run from north to south. They also found a layer of limestone approximately thick at the top of the cenote, upon which the temple sits.
Recent archaeological investigations have used electrical resistivity tomography (ERT) to examine the construction sequence of Kukulcán.