Teotihuacan was at its peak between 150 BC. and 450 AD, with an estimated 200,000 residents, making it then the largest city in the Americas, larger than Rome and likely the largest city in the world during that age. Yet experts are uncertain as to who built it and why it was suddenly abandoned around 700 AD. For years, archaeologists thought the city was of Toltec origin, but have since determined that the Toltec civilization came later, as did the Aztecs who believed Teotihuacan was a divine city. Sometime during the 7th or 8th Century, Teotihuacan was set aflame and abandoned. Again, the reason remains a mystery.,MORE