At some thirty meters tall, the Great Pyramid divides the site into northern and southern sectors. Access to the northern ceremonial precinct of Complex A was probably limited to the elite, who may have lived on the largely unexcavated Stirling "Acropolis." La Venta's rulers oversaw a burgeoning economy that included trade in exotic materials such as greenstones, much of which was buried in the elaborate offerings of Complex A. The site's ceremonial architecture is notable for use of local materials. Complex A, in particular, was the scene of four construction phases marked by the use of local clays and sands in a variety of colors. The southern sector, Complex B, includes a large plaza where numerous whole and fragmentary monuments have been discovered. It probably served as the primary staging area for ritual performances by La Venta's rulers. Colossal heads of stone, some reaching more than seven feet in height and striking in their individuality, are thought to depict the ancient rulers. Distinct headdresses adorn each head, underscoring their different personalities. Much of the iconography at the site reflects its environmental diversity and stresses the importance of the ruler's role in mediating between the watery realms occupied by fish, alligators, and sharks, and the earthly realm of agricultural and animal fertility.