Vergina, about 70 km west of Thessaloniki, is where the royal tombs of ancient Macedon were discovered in 1977 — Philip II, father of Alexander the Great, is among those buried here. The underground museum is one of the finest archaeological sites in Greece. Drive there in about an hour.
Halkidiki is the three-pronged peninsula south of Thessaloniki and one of the most beautiful coastlines in the Mediterranean. The beaches on the first peninsula (Kassandra) are the most developed and closest to the city; the second (Sithonia) is quieter and more wooded. The third, Athos, is a monastic republic where women are not permitted and male visitors must apply for a special permit months in advance.
Mount Olympus is a 2.5-hour drive south but the effort is worth it for committed walkers. The highest peak, Mytikas (2,918 m), can be reached in a two-day climb with an overnight at a mountain refuge. Even a short walk up through the forests above the town of Litochoro is impressive.