English: The first great Central Mexican highland culture of the Classic period had its capital at Teotihuacan, the City of the Gods located about 50 km northeast of Mexico City. At its height about the 4th century, this was a teeming metropolis of 100,000 or more inhabitants, with a well defined class structure. The city was laid out on a grid plan, with the Avenue of the Dead forming the main north-south axis. Monumental ceremonial pyramids, including the Pyramids of the Sun, Moon, and Feathered Serpent lined the avenue. Its people had knowledge of writing and books, a bar-and-dot number system, and a 260-day sacred calendar. A society seemingly based on agriculture, obsidian mining and trade, Teotihuacan held widespread influence throughout Mesoamerica. By the 9th century, the city was abandoned. Possible causes of this collapse include famine, volcanic eruptions, and invasion by outsiders. The ASTER image covers an area of 5.1 x 9.4 km, was acquired on March 11, 2002, and is located at 19.7 degrees north latitude, 98.8 degrees west longitude.