Why go
This history gives a route through the ancient city: begin with the Forum, then look toward the palace complex, Arch of Galerius and Rotunda. Their scale makes more sense when you know that Thessaloniki stood on Via Egnatia and became an imperial administrative centre.
The full story
Cassander founded Thessaloniki around 315 BCE and named it for his wife Thessalonike. After Macedon came under Roman rule, the city gained from its place on Via Egnatia, the road that crossed the southern Balkans toward Byzantium. Routes from the Balkan interior also met the coast here, giving Thessaloniki a role in trade as well as government. In the late Roman period, Emperor Galerius established an imperial centre in the city. The surviving palace remains, triumphal arch and Rotunda make that ambition easier to picture than a list of rulers would. Christianity also took root here in the Roman era; the later church of Agios Dimitrios commemorates the city's patron saint. The Forum and Galerius monuments are separate sites in the modern street grid, so reading them together reveals the former city's reach. Their setting among ordinary streets is part of the experience: ancient Thessaloniki survives as pieces within a living centre.