The lower and upper front doorways of Structure XX were designed as open monster mouths similar to that of Structure II . However, the outer walls of both the upper and lower vaulted rooms, which supported the front-facing monster masks, has fallen and taken the frontal masks with them. Only profile monster mouths are left to bracket the doors on the upper and lower levels. In addition, four superimposed monster masks remain on each of two of the corners of the superstructure.
Eaton states, "Structure XX dates to the late facet of the Chintok ceramic phase of the early Terminal Classic period. Apparently it is the last architectural monument built at the site. The two-story, multiroom temple-palace displays not only a continuation of the ornate façade tradition which evidently exalts Itzamna, but shows a greater elaboration than that of Structure II. Architecture and the associated religious symbolism reached their greatest development at this time.
By the end of the Chintok phase, ca. A.D. 830, all monumental building activity had ceased at Chicanna. It seems probable that the regional complex social organization and the importance of the Itzamna cult also declined during this time."