Kavala climbs a headland in a cascade of houses, crowned by a Byzantine castle and crossed by a 16th-century Ottoman aqueduct. It was ancient Neapolis, the port where St. Paul landed in Europe, and later the tobacco capital of the Ottoman Empire, whose merchants built the grand mansions of the Panagia old town. The Imaret, Muhammad Ali's 19th-century seminary, is now one of Greece's most storied hotels.