The archaeological site of ancient Sicyon lies on a plain area of the Vasilikos hill; it includes the excavated area of the Agora of the Hellenistic and Roman city, the Theatre, the Stadium and the Roman Baths (Balaneion), which have been restored and modified in order to be used as a Museum.

A temple excavated in the Agora (1) and dated from the Archaic to the Hellenistic period, was turned into a Basilica during the early-Christian period.

A Gymnasium ? Palaestra (2), dated to the Hellenistic and Roman periods, dominates the southwestern part of the Agora, at the foothills of the Hellenistic citadel (Acropolis). This monumental complex spreads over two levels, connected by three staircases. Of particular interest are the two fountains, located along the upper retaining wall.

In the eastern excavated section of the Agora have been revealed two 4th-century B.C. buildings, the Bouleuterion (3) and a long Stoa (4). During the Roman period the Bouleuterion was turned into a public bath (Thermes), while the Stoa was used as a workshop.

The Theatre (5) was carved into a natural depression at the foothills of the Hellenistic Acropolis and dates back to the late 4th century B.C. It consists of the Koilon, the Orchestra and the Scene (stage-building); the two vaulted passages at the sides of the Koilon, used for the entrance of the spectators, constitute unique examples of the Hellenistic architecture. During the Roman era several adjustments were made to the building, especially the Scene.

The Stadium (6) has not yet been excavated; it has, however, been located west of the Theater, due to the landscape: its southern part, the sphendone, is still visible, while the northern end of the track is retained by a wall.

Since 1935 the archaeological Museum of Sicyon (7) is housed in a section of the Roman Baths (Balaneion), in the northern part of the city?s Agora. In the atrium and the three halls of the museum are exhibited treasures from Sicyon and the surrounding areas, artefacts from the cities of Stymphalos and Pellene, as well as the cave of Pitsa; the objects are dated between the Mycenaean and the early-Christian period.