 Zaculeu was likely originally developed because of its proximity to the Seleguá River , providing a permanent water supply and transportation waterway , together with its easily defensible hilltop location . Zaculeu has 43 structures . The majority of construction activity took place in one burst in the Early Classic , with minor alterations thereafter . The smaller platforms situated in the plazas were late additions ; they show the influence of central Mexican civilization . The entrance to the site was via a narrow land bridge to the north , which was protected by a fortified structure that occupied three @-@ quarters of the width of the land bridge . 
