With its mineral wealth and safe harbour, ancient Thassos prospered from Classical to Roman times. The largest excavated area is the agora, a little way back from the fishing harbour. The site (free) is fenced but not always locked, and is most enjoyably seen towards dusk. Two Roman stoas are prominent, but you can also make out shops, monuments, passageways and sanctuaries from the remodelled Classical city. At the far end of the site (away from the sea) a fifth-century BC passageway leads through to an elaborate sanctuary of Artemis, a substantial stretch of Roman road and a few seats of the odeion. The nearby archeological museum is closed indefinitely for extensive expansion.

From a temple of Dionysos behind the fishing port, a path curls up to a Hellenistic theatre , fabulously positioned above a broad sweep of sea. It's currently open, but is a chaos of excavation, with summer-festival performances set to resume in the distant future. On the same corner of the headland as the theatre, you can still see the old-fashioned kaikia being built, and gaze across to the uninhabited islet of Thasopoula. It's possible to rent boats from the fishing harbour, self-skippered or not, to take you there and elsewhere.

From just before the theatre, the trail winds on to the acropolis , where a Venetian-Byzantine-Genoese fort arose between the thirteenth and fifteenth centuries, constructed from recycled masonry of an Apollo temple which stood here. You can continue, following the remains of a massive circuit of fifth-century walls to a high terrace supporting the foundations of the Athena Polyouhos (Athena Patroness of the City) temple, with Cyclopean walls. An artificial cavity in the rock outcrop just beyond was a shrine of Pan, shown in faint relief playing his pipes. From behind the summit, a rock-hewn stairway provided a discreet escape route to the Gate of Parmenon, the only gate in the fortifications to have retained its lintel; it's named from an ancient inscription ("Parmenon Made Me") on a nearby wall slab. From here a track, then a paved lane descend through the southerly neighbourhoods of the modern town, for a satisfying one-hour circuit.