sentences:  Structure D-11 is an artificial platform supporting the southernmost cluster of buildings in the group, it is accessed via the causeway.Structures D-12, D-13 and D-14 form another small plaza group, the plaza has an area of and is open on the southern side.The masks for which the site is best known were found on Structure A-2 and are known from three parts of the structure where they appear to have flanked the principle stairway.