Probing the mysteries of stars billions of miles into the past is all in a night's work at the futuristic Observatorio Interamericano Cerro Tololo, which sits at 2200m atop its hill. And while visitors can't stargaze through its monstrous telescopes (even the astronomers don't do that as the telescopes first feed data into computer monitors), a daytime tour of the facilities is still an enlightening experience.
Operated by the Tucson-based Association of Universities for Research in Astronomy (AURA, a group of about 25 institutions, including the Universidad de Chile), Tololo has an enormous 4m telescope. Free bilingual tours take place on Saturday only; make reservations at least one month ahead in high season. Two-hour tours are held at 9am and 1pm. There is no public transportation so rent a car or taxi, or arrange to come with a tour operator (you'll still need to make your own reservations with the observatory). After making reservations, pick up a permit to visit the facility from their administrative office in La Serena.