Calar Alto is the highest peak (2168 m over sea level) in the Sierra de Los Filabres, a mountain subrange of the Sierra Nevada in Andalusia, Spain. It is also the highest peak in the said mountain subrange.

It hosts the Calar Alto astronomical observatory, which benefits from two aspects of the climate in the region: the dry atmosphere reduces the restrictions that atmospheric water vapor adds to the transmission characteristics of seeing through the atmosphere (see also the article Tabernas Desert), and the low number of cloudy nights adds nicely to the efficiency of observations through the year.