"Looking at the map of Yaxchilan, one sees that the entire Main Plaza is oriented from northwest to southeast. Several small buildings sit perpendicular to this axis, and their apertures face southeast, the same direction as the plaza. Bisecting this major axis is a strong axis in the form of the stairway to Structure 33, the temple itself, and the group of monuments in the center of the Main Plaza. All these face northeast...This is not accidental, nor is it common at other Maya cities.
At Yaxchilan's latitude, the sun rises at 115-116 degrees on winter solstice. Like the summer solstice orientation group, the winter solstice buildings are set slightly outside the path of the sun. Again, this allows for a few minutes of illumination of the interior of the buildings, providing the trees at the southeast end of the plaza were kept cut. Note that all the winter solstice alignments are found on the Main Plaza, where no tall buildings block the path of the sun on winter solstice. So these alignments suggest that at Yaxchilan, winter solstice was the time and direction for the commemoration of the deceased.
The buildings and stelae which face summer solstice, on the other hand, all document Period Endings, accessions, captures, and sacrifices of living kings. Almost every building with associated sculptural or hieroglyphic monuments faces one of these two directions, and the few that do not seem to have been oriented in response to other specific concerns."
Carolyn E. Tate, Yaxchilan: The Design of a Maya Ceremonial City, p. 111