Monte Alban Ruin Site Oaxaca, Mexico, 599 BC-750 AD the oldest stone city in Mexico. Zapotec builders laid out the stone platforms running the length of the quarter mile plaza with a north south orientation 1,300 feet above the River Atoyac and the alluvial valley. Starting in 500 BC, they quarried stone from the hilltop and flattened the peak to make a broad level plaza. By 300 AD the population had risen to 30,000 people. The city has tombs primarily on the eastern and northern slopes, and five ball courts, two excavated and stabilized.