The archaeological site at Kotzia Square, opposite the Athens City Hall, yielded many important archaeological finds. It is located directly outside the ancient city's fortification, part of which was also revealed and is currently preserved in front of the National Bank of Athens building and at the Aiolou pedestrian precinct. Excavations revealed three ancient streets, a dense cemetery dating from the Protogeometric period (ninth century BC) until the Late Roman period (third century AD), a large complex of pottery workshops of the Late Roman period (late third - fourth century AD), and several houses.


Part of the famous Acharnean Street, which began at the city gate (currently in front of the National Bank of Greece building) and led towards the northern demes of Attica, occupies the centre of the archaeological site. Stratigraphical evidence indicates that the street was laid out in 480 BC and was widely used throughout the fifth century BC.


The cemetery stretched on both sides of Acharnean Street. The grave gifts found in association with burials and cremations cover a wide time span. They include all manner of terracotta vases, some of them by famous ancient pottery workshops, human and animal figurines, glass and terracotta unguentaria, bronze mirrors, gold jewellery, coins, and other objects. A large number of sculptures from funerary monuments, such as columns, pillars, and marble vases, were discovered throughout the excavated area. Many of these were inscribed with the names and origin of those buried in the cemetery.


During the second half of the third century AD, after the devastating invasion of Athens by the Heruli, the cemetery fell into disuse, and a large complex of pottery workshops covered much of its area. The workshops operated during the fourth century AD, a period of prosperity for Athens. Archaeological finds from inside and around the pottery kilns show that they produced vases, domestic utensils, lamps, roof tiles, and antefixes.


The excavations at Kotzia Square were conducted in 1985-1988 during the construction of an underground car park and covered an area of 7,000 square metres. Additional investigation took place near the car park's entrance and exit points in 1998-1999. Parts of the excavated area were conserved and fenced in 2003-2004, and are now accessible to visitors.