"On this surprising building, whose façade repeats the same theme over and over like a litany, the precise sense of composition transforms what could have been only monotony into fascination. Designed with absolute rigor, each element fits into the general composition without the slightest margin of error. Thus, while the rows of masks that cover the frieze continue uninterruptedly the lenght of the façade, those that cover the lower wall and are aligned vertically with the others are clearly divided by the door frame (whose total width is exactly the space corresponding to the sum of the whole mask and two halves, excluding the noses of those next to the doorways)."
Paul Gendrop, Rio Bec, Chenes, and Puuc Styles in Maya Architecture, p. 184
NOTE: The Maya show a fascination with tiling patterns used to cover areas. Here, masks on the lowest level do not line up in exact vertical columns with masks on the lower wall due to the double earplugs of the lowest masks. However, the periodicy of these lower masks cause them to align squarely underneath each doorway, where the noses widen out to form entrance steps to the chambers behind.