Τhe Agora museum is housed in the Stoa of Attalos, a reconstructed building of around 150 B.C. The characteristic feature of the mseum is that the exhibits are all closely connected with the Athenian Democracy, as the Agora was the focus of the city's public life.

The Stoa of Attalos was discovered during the excavations carried out by the Greek Archaeological Society between 1859 and 1902. In 1953-56 it was reconstructed in order to house the finds from the excavations at the Agora. In 1957 the Greek state assumed responsibility for the administration and security of the museum and the archaeological site.