Moon, Venus, and Athens National Observatory
Moon and Venus shine in a summer evening twilight of Athens. The historic building of the National Observatory of Athens is on the lower left and at lower right is the Temple of Hephaestus in the ancient Agora. The national observatory is a research institute founded in 1842; one of the oldest research institutes in Southern Europe. But the astronomical history of this location goes much further back in time. The observatory is next to the Pnyx, a rocky hill in central Athens the Athenians gathered to host their popular assemblies, as early as 507 BC. It was also where astronomer Meton made observations of the summer solstice in 432 BC, using an instrument named the heliotropion that made him identify his famous calendrical cycle (learn more on UNESCO Astronomy and World Heritage Portal).