platforms. The mounds and platforms were built largely from local sands and clays. It is assumed that many of these platforms were once topped with wooden structures, which have long since disappeared. Complex C (The Great Pyramid) Complex C, "The Great Pyramid," is the central building in the city layout, is constructed almost entirely out of clay, and is visible from a distance. The structure is built on top of a closed-in platform—this is where Blom and La Farge discovered Altars 2 and 3, thereby discovering La Venta and the Olmec civilization. A carbon sample from a burned area of the Structure C-1's surface resulted in the date of 394 ± 30 BCE. One of the earliest pyramids known in Mesoamerica, the Great Pyramid is high and contains an estimated 100,000 cubic meters of earth fill. The current conical shape of the pyramid was once thought to represent nearby volcanoes or mountains, but recent work by Rebecca Gonzalez Lauck has shown that the pyramid was in fact a rectangular pyramid with stepped sides and inset corners, and the current shape is most likely due to 2,500 years of erosion. The pyramid itself has never been excavated, but a magnetometer survey in 1967 found an anomaly high on the south side of the pyramid. Speculation ranges from a section of burned clay to a cache of buried offerings to a tomb. Complex A Complex A is a mound and plaza group located just to the north of the Great Pyramid (Complex C). The centerline of Complex A originally oriented to Polaris (true north) which indicates the Olmec had some knowledge of astronomy. Surrounded by a series of basalt columns, which likely restricted access to the elite, it was erected in a period of four construction phases that span over four centuries (1000 – 600 BCE). Beneath the mounds and plazas were found a vast array of offerings and other buried objects, more than 50 separate caches by one count, including buried jade, polished mirrors made of iron-ores, and five large "Massive Offerings" of serpentine blocks. It is estimated that Massive Offering 3 contains 50 tons of carefully finished serpentine blocks, covered by 4,000 tons of clay fill. Also unearthed in Complex A were three rectangular mosaics (also known as "Pavements") each roughly and each consisting of up to 485 blocks of serpentine. These blocks were arranged horizontally to form what has