Teotihuacan or the "Piramides de Teotihuacan" is an ancient city in Mesoamerica, built originally in the first two centuries BCE and expanded upon and made great in the first to second century AD. In its heyday, Teotihuacan was the sixth largest city in the world and is home to beautiful monuments like the Avenue of the Dead and the Pyramids of the Sun and Moon. The actual culture and even language of the people who built this city has been lost to history.
The most notable monuments are the Avenue of the Dead, the Pyramid of the Sun, the Pyramid of the Moon and Ciudadela where the Serpent Feather Pyramid lies. These were built around the same time as the city, around the second century BCE. However, the architect and the people who worshipped/utilized them remain a mystery.
It is thought that human sacrifice occurred at the pyramids as many tombs have been uncovered. The Pyramid of the Sun is the third largest pyramid in the world, beaten only by Cheops’ Pyramid at Giza and Cholula Pyramid in Mexico.
The Avenue of the Dead was the main thoroughfare of the city, connecting the massive pyramids and other monuments of the city. All of these monuments were built of earth and stone. The city was built to be the religious center of Mexico and at its height, it had over a hundred thousand citizens.
Unfortunately, little else is known about the dwellers of this city, their culture, and even why they disappeared. There is evidence of a fire sweeping through the city which may have destroyed large parts of it and forced the citizens to move out, but this is speculation. All that is known is that around 700 AD, the greatest city in Mesoamerica abruptly emptied, leaving behind these ruins.