Unlike most Greek islands, Rhodes it's not the classical vestiges (although there are) to define the image. Infact, the maximum splendor of the island was during the Middle Ages. Much of what is now known as the Old Town (UNESCO World Heritage Site since 1988) belongs to this era.
However, after the Ottomans drove the Knights of St John off the island, the ancient and medieval traces of Rhodes were largely compromised. Much of what has been saved, then transformed into a tourist attraction for the island, is due in part to the Italians, who governed Rhodes from 1912 to 1943, and then to the Greek government after the Second World War.
There are so many things to see: in the medieval Citadel we remember the Archaeological Museum, the Palace of Grand Master and the Cathedral of St. John. Also not to be missed is Nea Agorà, the island's market; the Byzantine monastery of Filerimos in the district of Ialyssos; the acropolis of Lindos and, of course, the many beaches and nightlife opportunities.