 Structure 13 is on the southwest side of Plaza 1 , dividing that Plaza from Plaza 2 . It was accessed via a double stairway ascending from Plaza 1 . This double stairway gave access to the first level of the temple structure only ; from there , a wide single stairway continued to the summit shrine . Only the lower sections of the walls and columns of the temple superstructure remain . The earliest phase of construction dates to the Early Classic and consisted of a low platform that supported a perishable superstructure . 
