I early June I spent two weeks in Greece, including a week on a large sailboat, The Star Flyer.  We cruised the islands, perhaps the most interesting was Santorini, the town of Threra had been overwhelmed in a volcanic eruption about 1620 BC.   It was preserved like Pompeii  and excavated in the past century.  Athens was very crowded but the old ruins, like the Parthenon are wonderful.