Built into the granite cliffs at the mouth of the Rio Douro, the hilly city of Porto presents a heady juxtaposition of eras and styles. Here, medieval alleyways, orderly neighborhood squares, and ornate Baroque churches readily intermingle. Porto’s historic heart is a UNESCO site of winding lanes, zigzagging staircases and tiled churches. The highlight, though, is a taste of port wine at its best – a happy accident dating from the 17th century when brandy was discovered to preserve wine for transit. After your choice of palate-pleasing shore excursions, return for an onboard fado folk music performance.