Building 12 is one of Yaxchilán's plainest structures architecturally speaking. Its interior consists of two parallel passageways covered with the typical mayan corbelled vault. Entrance is gained through any of the nine openings: seven on the main façade and two on the sides. This building's more important feature is the presence of eight lintels with hieroglyphic texts carved on their undersides. Of these, three are in situ, two are on display at the National Museum of Anthropology and one is in the British Museum. Together, they apparently make up an ancient listing of the city's ten earliest rulers who shaped the destiny of Yaxchilán in the first half of the sixth century.
From the INAH sign at the site