It is located in the Casma Valley. Some of the largest prehistoric monuments around the world are situated in the Casma Valley and in the Sechín Valley. The pyramid, Main Square, and circular sunken courtyard complexes extend over one kilometer in length. In February 2008 archaeologists uncovered a ceremonial plaza which has been dated to 5,500 years ago.
German and Peruvian archeologists work at the circular 5,500-year-old sunken ceremonial plaza, built of stones and adobe, part of the Sechin Bajo archaeological complex in Casma, Andes foothills, 330 kilometers (206 miles) northwest of Lima, Feb. 2008. The archeologists say the plaza is the oldest known monument in Peru.
