The Stoa of Attalos is thought to have been a kind of ancient commercial center with 21 shops on each of the two floors lining the western wall. Visitors may get an idea of everyday life in ancient Athens through the collection of everyday objects which were unearthed in excavations. The stoa's dimensions are 115 by 20 m wide (377 by 65 ft wide) and it is made of marble from Mt. Penteli and limestone.
The Stoa of Attalos(or Attalus), is one of the most impressive buildings in the Athenian Agora. It was built by, and named after, King Attalos II of Pergamon, who ruled between 159 BC and 138 BC. Typical of the Hellenistic age, the stoa was more elaborate and considerably larger than earlier buildings of ancient Athens of the same purpose and use.
The stoa is identified as a gift to the city of Athens for the education that Attalos received here. A dedicatory inscription on the architrave is engraved as built by Attalos II, ruler of Pergamon from 159 BC to 138 BC. The stoa was in frequent use until it was destroyed by the Heruli who invaded Athens in 267. The ruins became part of a fortification wall, which made it easily seen in modern times. 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 Theater of Dionysos. The main difference is that the Attalos' stoa had a row of rooms at the rear on the ground floor that have been interpreted as shops.
The building skillfully makes use of the different architectural orders. The Doric order was used for the exterior colonnade on the ground floor and the Ionic for the interior colonnade. This combination had been used in stoas since the Classical period and was quite common by Hellenistic times. On the first floor of the building, the exterior colonnade was Ionic and the interior Pergamene. The rooms of both stories were lighted and vented through doorways and small windows located on the back wall. There were stairways leading up to the second floor at each end of the stoa.
In the 1950s, the Stoa of Attalos was fully reconstructed on the original foundations using the original materials found on site and made into the Ancient Agora Museum, by the American School of Classical Studies at Athens, with funding donated by the Rockefeller family.
The Museum of the Ancient Agora exhibits are mostly connected with the Athenian democracy. Among the many interesting exhibits is the klepsydra, a water-clock used for timing the speakers, as well as ancient ballot boxes for voting. The collection of the museum includes clay, bronze and glass objects, sculptures, coins and inscriptions from the 7th to the 5th c. BC, as well as later pottery.
The ceremony of the signing of the 2003 Treaty of Accession of ten countries to the European Union was conducted in the Stoa of Attalos on 16 April 2003.