The collection of the museum includes clay, bronze and glass objects, sculptures, coins and inscriptions from the 7th to the 5th century BC, as well as pottery of the Byzantine period and the Turkish conquest.

Typical of the Hellenistic age, the stoa was more elaborate and larger than the earlier buildings of ancient Athens and had two rather than the normal one storeys.

The building is similar in its basic design to the Stoa that Attalos' brother, and predecessor as king, Eumenes II, had erected on the south slope of the Acropolis next to the Theatre of Dionysus.

[4] In 1948, Homer Thompson (who was field director of the Agora excavations from 1946–1967 being undertaken by the American School of Classical Studies at Athens (ASCSA) proposed that the Stoa of Attalos be reconstructed to serve as a museum to house archaeological finds.

[1] His proposal was accepted and so in June 1953, Ward M. Canaday (president of the Board of Trustees of ASCSA from 1949–1964) authorized the beginning of the work, and in January 1954, the landscape program was formally inaugurated.

[5] The plans were drawn by John Travlos, architect of the Agora excavations, while the reconstruction was supervised by the New York architecture firm of W. Stuart Thompson & Phelps Barnum.

[5] The building was reconstructed on the original foundations but in order to facilitate its new role as a museum some changes were made to the basement storage area, window sizes and door positions while some internal walls were eliminated.

[5] The reconstruction is particularly important in the study of ancient monuments because it is a faithful replica of the original building, to the degree possible within the limits of archaeological knowledge.

[7] The ceremony of the signing of the 2003 Treaty of Accession of 10 countries – Cyprus, the Czech Republic, Estonia, Latvia, Lithuania, Hungary, Malta, Poland, Slovakia, and Slovenia – to the European Union was conducted in the Stoa of Attalos on 16 April 2003.