sentences:  It includes a pyramid, range structures, and various mound groups and terraces, the major period of occupation at Group A dates to the Late Classic.The group mainly consists of residential structures and includes several palaces, only two or three of which had vaulted stone roofs, the rest of them were likely to have been roofed with palm.Group A began in the Early Classic with very few structures but underwent a major expansion in the Late Classic, with the construction including formal stone palaces with corbel-vaulted roofs and covered in painted stucco.