Dzibilchaltun (pronounced Ts’íibil Cháaltun) is a comparatively small Maya archaeological site in the Mexican state of Yucatán, approximately 15 kms (10 miles) north of the state capital Mérida. It is in the extreme north of the Maya Region, not far from the Gulf of Mexico. The site has been continuously occupied for about 3,000 years up until the arrival of the Spanish, and is known to be the longest functioning city of the Mayan world.
An interesting feature of the temple occurs on the Spring and Fall equinoxes, the beginning of the planting and harvesting seasons. The doorways were constructed to capture the light of the rising sun on those days. As the sun rises it is visible directly through one door of the temple and out the other, filling it with sunlight.
Source: http://www.mayan-ruins.org/dzibilchaltun
There is also a nice little cenote available to go swimming in.
