More than 50,000 protesters massed in the streets of northern Greece’s biggest city Thessaloniki on Sunday, police said, in a long-running row between Athens and Skopje over the use of the name Macedonia. Athens argues that the name Macedonia suggests that Skopje has territorial claims to the northern Greek region of the same name, of which Thessaloniki is the capital. The region was the centre of Alexander the Great’s ancient kingdom, a source of Greek pride. Hardline clerics, far-...