The ruins, measuring 180 by 120 meters, were found at Sechin Bajo in Casma, north of the country's capital Lima. The plaza, believed to have been built between 3,500 B.C. and 3,000 B.C., is one of the oldest discoveries in Latin America.
The El Comercio newspaper cited Peter Fuchs, director of the Sechin Bajo archaeological project, as saying: "Whoever built Sechin Bajo had advanced knowledge of architecture and construction."
Experts said that older structures could be found underneath the site.
"There are four or five plazas deeper down, which means the structure was rebuilt several times, perhaps every 100 to 300 years," thetechherald.com cited archaeologist German Yenque as saying.
The oldest previously discovered building near Sechin Bajo had been dated at 3,600 B.C.
The finding signals that civilization in Peru was flourishing at the same time as in the Middle East and South Asia.
