Teotihuacan in Mexico City was built around 100 B.C. and was already in ruins by the time of the Aztecs. It still stands today and many artifacts are found daily in Teotihuacan, and the surrounding areas. It was made a World Heritage Site in 1987 and finds itself in an odd spot with increasing property values and a 21st century society . The city is clear and within sight when you find yourself on top of the sun pyramid.
pyramid of the sun + view from the top
Pyramid of the moon + view from top.