Originally all three temples in the Cross Group looked much like the Temple of the Sun, the best preserved member of the Group.
"Chan-Bahlum pursued the triadic theme further in the design of the buildings themselves. In each temple, three doors pierce the front wall of an interior which is divided into an antechamber and three rear sanctums. In the central chamber of each temple his masons built the holy portals which opened into the Otherworld.
These powerful foci of supernatural energy were set inside miniature houses--called by the Maya pib na or ""underground buildings" — built within the back chamber of each temple. While these little houses were only symbolically underground, they replicated in principle the real underground buildings of Palenque: the tombs of Pacal and other kings in pyramids which dotted the sacred landscape of the city."
Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the Ancient Maya, p. 238-9
From the Maudslay Collection, British Museum. Used with permission under the CC BY-NC-SA 4.0 non-commercial license. ©The Trustees of the British Museum.
"Artists decorated the outer facades of the temples whith huge plaster reliefs modeled on the roof combs, the entablatures, and on the piers between the doors. Unfortunately, only the sculptures of the Temple of the Cross entablature remain legible.
These depicted frontal views of great Witz Monsters gazing out from all four sides of the roof. The Maya thought of this temple as a living mountain. Thus, its inner santuary was "underground" because it was in the mountain's heart."
Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the Ancient Maya, p. 239
Drawing by Linda Schele, © David Schele, courtesy Foundation for the Advancement of Mesoamerican Studies, Inc., http://www.famsi.org
Photo courtesy of Kasper de Jonge and Jeroen Schoenmakers of the Netherlands
Sanctuary Tablet in the pib na of the Temple of the Sun has images of war and death sacrifices. Chan Balam and Pacal face each other across a Sun Jaguar shield and crossed spears.
Images of war and death sacrifice adorn the panel in the pib na of the Temple of the Sun. A Sun Jaguar shield and crossed spears dominate the central icon. These images are sustained aloft by a throne with bleeding jaguar heads emerging from one axis, and bleeding dragons from the other.
The throne and its burden of war rest on the shoulders of God L and another aged god from the Otherworld. Both are bent over like captives under the feet of victorious warrior kings. This scene recalls the defeat of the Lords of Death at the beginning of time by the Hero Twins. Captive sacrifice was the source of life through the reenactment of the magical rebirth of these heroic ancestors of the Maya people. God L, who received the greetings of the new king in the Temple of the Cross, now hold up the burden of war and sacrifice. In both cases, ritual performance by the king involved otherworld denizens in the human community.
Here in the Temple of the Sun, the power object is not actually passed from the inside scene to the outside, as in the other temples; but the intent of the composition is still the same. On the inner panel, Pacal holds a full-bodied eccentric flint and a shield made of a flayed human face: symbols of war among the nobility of Palenque and other Maya kingdoms.
If we move to the outer panels, on one we see Chan-Bahlum holding a bleeding jaguar on a small throne as the symbol of sacrificial death. On the opposite panel, he wears cotton battle armor with a rolled flexible shield hanging down his back. The tall staff he wields is probably a battle spear typical of the kind carried by warrior kings at other sites. The parallelism here is nicely rendered. On the one side, he is emerging from the pib na as a warrior prepared to capture the enemies of his kingdom; on the other, he comes forth as the giver of sacrifice, the result of victory.
Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the ANcient Maya, p. 243