neighboring Chunchucmil, during the Middle Classic). The architecture is best understood and is almost always broken up into four groups and then looking at how architecture changed or didn't change within those groups. The four groups are: May, Satunsat, and Ah Canul/Canul and Dzib. These groups make up the urban center, and are almost exclusively monumental architecture. They were defined by the excavation team and they're essentially just a cluster of buildings, or a building (Madrid, 1991). There's much more than just these four groups; the rest just hasn't been excavated really, since there was such a heavy focus on excavating monumental architecture. Most of what's been excavated at Oxkintok is temples, palaces, and multiroom structures. To trace the changes in architecture of the site, the above chart (Fig. 7) was compiled. It's a compilation of data from the three sources listed below figure 7. It is evident that there are many major changes between the three periods, and in general it's a transition from irregular design to a more elaborate, very planned out geometric design with decoration and complex stucco art and stone wrought decorations. One thing that remains consistent the use of domes and arches for entryways and open spaces. Concerning the individual groups, there's a concentration of Proto Puuc in the Ah-Canul group and Early Oxkintok in the May group that was later modified in the Proto Puuc phase, but no group is confined to one phase. Satunsat The most popular structure at the site is the tzat tun tzat (sometimes written Satunsat, but most commonly called "The Labyrinth"). The Satunsat group is an outlier. It's a single building, a sort of a maze or labyrinth, built to replicate a cave complex. There's no real guess as to what it was built for, though there was a recent discovery that most of the ventilation shafts line up with specific positions of the sun, so some think it was a maze used for initiation and practice of religion but there's nothing conclusive. So it's a little hard to place Satunsat into any one phase, but sources continuously point to a probability that this structure was built in the early Oxkintok phase. In the VI century, one of the rooms of the lower floor was converted into a burial chamber with a reduced area of the labyrinth. The staircase to the third floor on the north side was also