We docked in Porto Corsini and were in Ravenna center in 15 minutes. The city feels like a quiet university town until you step into San Vitale and the entire dome explodes with emerald-green, sapphire, and 24-karat gold mosaics of Justinian and Theodora staring down with emperor eyes. I actually gasped out loud. These are the world's finest 5th and 6th century Byzantine mosaics — surfaces shimmering with tesserae of gold leaf pressed between glass, still radiant after 1,500 years. The blues are so deep they feel like windows into heaven itself.

The Mausoleum of Galla Placidia is tiny but the deepest blue starry sky you'll ever see — it feels like being inside a jewel box where time stopped in 425 AD. Ravenna was the capital of the Western Roman Empire from 402 to 476, then the seat of the Ostrogothic Kingdom, then the Byzantine Exarchate. Every emperor and bishop tried to outdo the last with more gold, more color, more glory. In 1996, UNESCO designated eight of these early Christian monuments as World Heritage Sites: San Vitale, Galla Placidia, Sant'Apollinare Nuovo, Sant'Apollinare in Classe, the Arian Baptistery, the Neonian Baptistery, the Mausoleum of Theodoric, and the Archbishop's Chapel.

We visited five of the eight UNESCO sites on foot — each more jaw-dropping than the last. We had lunch — piadina romagnola at Ca' de Vèn — flatbread stuffed with squacquerone cheese and rocket that melts in your mouth. In the afternoon we visited Sant'Apollinare in Classe just outside town, where the mosaic apse with sheep and a giant cross in a green field made me tear up.

Then we walked to the Basilica of San Francesco and found Dante Alighieri's tomb tucked beside it — a simple neoclassical shrine with a single lamp that has burned since 1908. Dante died here in exile in 1321, banished from his beloved Florence for political reasons. Florence has repeatedly asked for his remains back; Ravenna has refused every time. There's something poignant about the greatest Italian poet resting in this quiet city of mosaics, far from the home that rejected him. I stood there a long time, thinking about exile and art and what it means to belong somewhere.