The Cahokia Mounds Historic Site is the one of largest pre-Columbian Native American cities in America at 600-1400 CE. This site cover near 2200 acres about 3.5 square miles and contains over 120 ancient made mounds in wide range of sizes, shapes and functions. \cite{wiki:xxx} The biggest Mound in Cahokia is the Monks Mound, figure \ref{fig:1}. It received its name from the group of Trappist Monks who lived on one of the nearby mounds.The beginning of its construction dates from 900-955 CE. The size was calculated in 1988 as about 100 feet (30 m) high, 955 feet (291 m) long including the access ramp at the southern end, and 775 feet (236 m) wide. Unlike Egyptian pyramids which were built of stone, the platform mound was constructed almost entirely
