During the years of Macedonia’s obscurity, Thassos becomes the devoted concomitant of Rome. In spite of this loyalty, this had as a result its cruel besiege. After Rome’s’ victory, Thassos turned against Macedonia.

However, in 80 BC Thassos gained a good recompense, when Leukios Syllas forced the Senate to provide to the city privilege and immunity and give back its territories in the main land.   Thassos redeemed its status, rehabilitated its trade and many wealthy Thassians began to interact in the political life of the area, operating as mediators between Thessalonica’s dignitaries and the rest of Greece. From an archaeological and residential point of view, this period of time does not show any activity and the information we have is rather little. In the city’s agora the “Loxi Stoa” is built and the monument of Theagenis is established.

Under the Roman occupation, Thassos remained free only in name. That is why Plinius refers to Thassos as free until the Flavian period, when Vespasianos (69-70 BC) united Thassos with the province of Thrace. From then on, it was actually a distant province of the mighty Roman Empire. It appears, however, that even though Thassos lost its freedom during those years, it regained its former prosperity, as testified by the rich sarcophagi that have been preserved form that era.

The Thassians also played a part in the last moments of the Roman Republic. In the last confrontation in Philippi between the republicans Brutus and Cassius and their opponents Antonios and Octavius, Thassos was used by the republicans as a base and provisioning centre. In this battle of Philippi, Cassius committed suicide and Brutus carried his body to Thassos offering the final honours. There too, after the second battle and the death of Brutus, many famous Romans took refuge. In the autumn of 42 BC, Antonios turned against Thassos and retaliated. Fortunately, this fall from favour did not last long as Augustus and his family restored the city’s former privileges. However, the development of the island was from that time affiliated to the Roman history and its emperors, fact which reflects in the social life and the capitularies of the island.

At the same time, the social evolution proceeded with jobs and money in the hands of a small number of families, while the women assumed hieratic duties, renovating sanctuaries at their own expenses. During the years of the empire, the government of Rome tries to reinstate the aristocracy, creating a new class, the “friends of Caesar and homeland”, a title conferred upon most of the distinguished Thassians of the 1st century AD. At the end of the 2nd century AD, a Senate was included in the authorities. The high priests of Augustus worked on constructions, bids and presentations, in order to show their wealth. They invited gladiator fights, “hunting” games and in the middle of the 2nd century they renovated the theatre. When the province of Thrace was created during the reign of Claudius, Thassos benefited by being relieved of the obligation of supplying troops or carrying out tasks for the mainland’s imperial postal service. Until the 4th century AD, Thassos relished prosperity. With the advent of Christianity, the number of Basilicas increased, as they did in Philippi where the Apostle Paul gave his first sermon on European ground. And finally, during the Byzantine period, Thassos became the house of the bishopric.