Greece is the southern anchor of any Balkan trip. Athens connects to Thessaloniki by the country's only fast train, and to Meteora by a direct InterCity from Larissa Station (4h15). The KTEL bus network covers everywhere the trains don't go.
Greece is in the EU and Schengen, uses the Euro, and is the easiest Balkan country logistically. From the northern Balkans you reach Greece by overland bus through North Macedonia (Skopje → Thessaloniki, 5h) or by ferry from Italy or Albania (Saranda → Corfu, 30 min). Meteora is the country's most-asked-about non-island destination; you get there by direct train from Athens to Kalambaka.
Best time to visit
April–June, September–October. Islands: May–early October only.