The Roman 'forum' (market place complex) of the time of the Antonines and the Severans (2nd-3rd century AD) was situated on the site where possibly the Hellenistic 'agora' once stood. Due to the incline, the buildings were disposed on two terraces (Upper and Lower Agora) connected by a stone staircase.
  The square Upper Agora was paved and surrounded by stoae (porticoes) with two-tiered columns and decorated floors. On the eastern side there was the library and the odeum. Because of the considerable difference between the two levels, a 'cryptoporticus' (double subterranean stoa) was constructed under the south portico of the Upper Agora; this structure faced the Lower and served as supporting wall for the Upper Agora and as refuge in bad weather.
  The facade of the 'forum' towards the Via Regia (present-day Via Egnatia) was splendid: the two-tiered southern stoa of the Lower Agora had a platform to the south-east and bore relief figures of Maenads, Dionysos, Ganymede etc. - today in the Louvre Museum - known as 'idols' or 'Las Incantadas' (the bewitched ones).

The text is cited from the webpage:
www.macedonian-heritage.gr/HellenicMacedonia/en/C1.6.1.html