  
By Joel Skidmore A major effort was focused on the walled platform surrounding Structure 3C1 (the Osario or High Priest's Grave; see map) and its associated constructions, including the aforementioned Sacbé 15 and the buildings at the edge of the Xtoloc Cenote, which are part of the same complex. If one exits in a straight line from the central chamber of the Xtoloc Temple (map), one passes a rectangular altar, then a peculiar formation that includes a cave. |
| Continuing down Sacbé 15 itself and passing through a portal in a wall, one encounters a platform with six tall columns that contains two burial vaults, probably for secondary interments; the Venus Platform (virtually a copy of the one in the main plaza); and a low, rounded platform with four stairways. |
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Finally one ascends the east stairway of the Osario and enters the sanctuary on top. From here, in the era of its construction, a flight of stairs and a tunnel communicated with a natural cave about twelve meters below the surface.
The Osario's exterior was richly decorated with serpents in varying relationships, mythological birds, men in god masks, man-bird-serpent combinations, and large "Chac" masks characteristic of the Puuc style. Atlantids and personages in bird masks must have formed part of the iconographic program of the sanctuary in its final phase, which was marked by incensarios and the burned bones of infants in the rubble. The entrance to the portico was flanked by feathered-serpent columns. Each of the eight ballustrades is decorated with two intertwined serpents, one feathered and one with a cloud motif. The top border of the pyramid is formed by eight interlaced serpents, four covered with turquoise disks and the others with jeweled earrings. The three upper levels of the pyramid (of a total of seven) were covered with stone tablets carved in relief with twin birds, each with the head of God K, surrounded by numerous fruits, cacao seeds and jewels. There were forty-eight tablets in all. |
| The upper part of the facade of the temple itself was adorned with sculptures depicting the man-bird-serpent hybrid that also appears on the Temple of the Warriors and the Venus platforms. Four tablets are carved in high relief with men in bird costumes and masks with beaks, who appear to be rotating in a dance movement with their arms extended. |
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