Sixty kilometres up the Elqui Valley from La Serena, near Vicuña, Mamalluca is the most popular of the public observatories in the area. Two-hour tours run every evening: a short talk on the southern sky, a look through the telescope at planets, nebulae, the Magellanic Clouds.
The skies here are among the clearest on Earth — which is why most of the world's major observatories (Cerro Tololo, La Silla, ALMA further north) are nearby. Mamalluca itself is a tourist observatory, not a research facility, but the views are still extraordinary. Book ahead in summer; tours fill up. Bring warm clothes — desert nights are cold.