The Calern Observatory (formally the Observatoire de la Côte d'Azur, site de Calern) sits on the Plateau de Caussols about 10 kilometres south of Gréolières, at an altitude of around 1270 metres. It is a working research facility operated by the Université Côte d'Azur, and one of the principal sites for laser ranging to the Moon — a technique that has been used here since the 1980s to measure the Earth-Moon distance to millimetre precision.
The observatory is not a conventional visitor attraction, but it opens to the public on certain evenings for guided sessions including telescope viewing. Check the observatory's website for dates, as they vary by season. The plateau around Calern is itself worth a visit: the high limestone plain is remote and largely unchanged, with few buildings and long views in every direction. On a clear night, away from the coastal light pollution, the skies here are some of the darkest within easy reach of the Riviera.