MEXICO CITY.- The Archaeological Zone of Tula, in the Mexican state of Hidalgo, will open its doors for the first time at night, to receive visitors for the academic event Los Caminos del Cielo, Noche de Observacion Astronomica (Roads of the Sky, Night of Astronomical Observation) to take place on Friday, September 10th 2010, where telescopes will be installed at the central esplanade of this Prehispanic site. The capital city of the Toltecas during the Early Post Classic period (950-1150AD) has been identified as the ancient Tollan Xicocotitlan and is considered a privileged location for astronomical observation due to its urban planning. According to Nahua informants of Bernardino de Sahagun, Toltecas were great sky observers, “they knew…the stars, they gave them names…knowing well how the sky moved, how it rotated”. Architectonic orientation