Kavála Citadel
Built by the Byzantines, the citadel has crenellated walls that boast excellent views down to the azure waters of the harbor below, as well as the usual ramparts and dungeons to explore. You'll walk through the Panagia, the old town, on your way up. Look out for the multi-domed Imaret, built in 1817 as a religious school and now a luxury hotel.