Also known as Structure 22A, the Popol Nah or House of the Council, is located at the northwestern edge of the East Acropolis. This building has a very characteristic mat pattern as the decoration on its façade, which has been reconstructed from the fallen pieces found by the Copan Mosaic Project. A mat was a symbol of power among the Maya. It is important to note that in Copan each building has its own unique “fingerprint” this is how scientist are able to differentiate the use of each building, the exterior decorations often gives clues and details about the use and its function.

So the mat design suggests that Structure 22A was a very important building, going over dictionaries of ancient Maya languages we find a literal translation for popol nah as “mat house” or “house of mats”. On different sources, such as the Popol Vuh, there are references where “mat houses” were also referred to as “Community House” or “House of Council”. According to these contexts the “ popol nah ” served as a meeting place for high ranking officials. Archaeologists have been able to reconstruct this building very accurately due to the way in which the remains were found, after the building fell into disuse, the mosaic patterns fell away in big blocks and often with sections of wall still attached, thus giving the basis for reconstruction and consolidation. Another piece of evidence to support this theory is that, surrounding Structure 22A, there are 8 mosaic compositions of a figure seated on top of a glyph, this is reminiscent of the seated rulers depicted on Altar Q. However, on Structure 22A -differing from the clear meaning of the glyphs below each ruler on Altar Q- the meaning of each glyph below each figure states a character's provenance or honorific title, rather than his personal name. The glyphs associated with Structure 22A, although yet undeciphered, tend to suggest a rank or a place name.

The construction of this building coincides chronologically (based on epigraphic as well as archaeological evidence) with thee political troubles that arose after the death of Waxaklajuun Ub'aah K'awiil at the hands of K'ak' Tiliw Chan Yoaat of Quirigua. The evidence suggests that a succeeding ruler tried to establish a different form of government for the Copan Valley, presumably to keep the people from leaving the valley for other cities such as Quirigua, effectively “inventing” a new formula to rule the valley with the “ popol nah ” and its councilors plus the king, thus involving the important players around the Valley in the affairs of state.