The National Observatory of Athens is a research institute in Athens, Greece. Founded in 1842, it is the oldest research foundation in Greece, as it was the first scientific research institute built after Greece became independent in 1829, and one of the oldest research institutes in Southern Europe.

The central premises of the National Observatory of Athens are situated at the historic site on top of Hill of the Nymphs at Thiseio. Nymphon Hill borders with Philopappou Hill and is opposite to the Acropolis and the Athenian Agora. They house the central administration as well as the Institute of Geodynamics.