Xochicalco was declared "World Heritage" by UNESCO in 1999. The heyday of this city took place in the Epiclásico period (650-900 AD), during which most of the buildings that we see today were built.
According to some researchers, Xochicalco came after the abandonment of Teotihuacán to fill the void of economic and political power caused by that fact.
They are of special interest the carved reliefs on the sides of some buildings. The temple of the "Feathered Serpent" has thin and stylized representations of the deity in a style which includes apparent influences Teotihuacan’s and Mayans.
The main attraction in the Archaeological Site is the observatory in a cave with steps inward, tilled, where during the Equinox, the sunlight illuminate creating an extremely bright beam of light.