A complex of impressive Greek and Roman ruins straddles both sides of the Tripoli road. The star attraction is the impressively large theatre, which originally seated 20,000 people. Dating from around 300 BC, it was greatly modified by the Romans in the 2nd century AD. Next to it is the impressively preserved wall of a Roman bathhouse; beyond is the 1st-century AD odeion (smaller covered theatre), whose origins date back to the 5th century BC. Across the road is the sizeable ancient agora.
From central Argos, head south along Danaou for about 500m and then turn right onto Theatrou.