 Teotihuacan was listed as a World Heritage Site by Unesco in 1987.Teotihuacan archaeological excavations continue to this day, and have resulted in a gradual increase in the quality and quantity of knowledge of the city's history; even so, such important facts as its original name and the ethnic affiliation of its founders are still unknown.It is known that it was a cosmopolitan place, however, by the documented presence of groups from the Gulf coast or the Central Valleys of Oaxaca.