Rhodes. Greece. The imposing 16th century d’Amboise gate in the Walls of the Knights. The old walled town of Rhodes is a UNESCO world heritage listed site and the best preserved and largest living medieval city in Europe. The 4km defensive walls were built by the Knights of St John during the 13th to 15th century to defend Western Europe against the expanding Ottoman Empire. Within the walls are a medieval warren of small alleyways and magnificent historical buildings. The island of Rhodes is the largest of the Dodecanese Island group.