Rhodes is an outstanding example of an architectural ensemble illustrating the significant period of history in which a military hospital order, founded during the Crusades, survived in the eastern Mediterranean area in a context characterized by an obsessive fear of siege. The fortifications of Rhodes, a 'Frankish' town long considered to be impregnable, exerted an influence throughout the eastern Mediterranean basin at the end of the Middle Ages.
The Order of St John of Jerusalem, also known as Hospitallers, occupied Rhodes from 1309 to 1523 and set about transforming the island capital into a fortified city able to withstand sieges as terrible as those led by the Sultan of Egypt in 1444 and Mehmet II in 1480. With the Palace of the Grand Masters, the Great Hospital and the Street of the Knights, the Upper Town is one of the most beautiful urban ensembles of the Gothic period. In the Lower Town, Gothic architecture coexists with mosques, public baths and other buildings dating from the Ottoman period. With its Frankish and Ottoman buildings, the old town of Rhodes is an important ensemble of traditional human settlement, characterized by successive and complex phenomena of acculturation.
The medieval city is located within a wall 4 km long. It is divided according to the Western classical style, with the high town to the north and the lower town south-southwest. Originally separated from the town by a fortified wall, the high town (Collachium) was entirely built by the Knights Hospitallers who, following the dissolution of the Templars in 1312, became the strongest military order in all Christendom. The order was organized into seven 'Tongues', each having its own seat. The inns of the Tongues of Italy, France, Spain and Provence lined both sides of the famous Street of the Knights, one of the finest testimonies to Gothic urbanism. Somewhat removed to the north, close to the site of the Knights' first hospice, stands the Inn of Auvergne, whose facade bears the arms of Guy de Blanchefort, Grand Master from 1512 to 1513.
The original hospice was replaced in the 15th century by the Great Hospital, built between 1440 and 1489, on the south side of the Street of the Knights; today the building is used as the archaeological museum. Located north-west of the Collachium are the Grand Masters' Palace and St John's Church. At the far eastern end of the Street of the Knights, built against the wall, is St Mary's Church, which the Knights transformed into a cathedral in the 15th century. The lower town is almost as dense with monuments as the Collachium. In 1522, with a population of 5,000, it was replete with churches, some of Byzantine construction; after 1523, most were converted into Islamic mosques.
Throughout the years, the number of palaces and charitable foundations multiplied in the south-south-east area: the Court of Commerce, the Archbishop's Palace, the Hospice of St Catherine, and others. The ramparts of the medieval city, partially erected on the foundations of the Byzantine enclosure, were constantly maintained and remodeled between the 14th and 16th centuries. Artillery firing posts were the final features to be added. At the beginning of the 16th century, in the section of the Amboise Gate, which was built on the north-western angle in 1512, the curtain wall was 12 m thick with a 4 m high parapet pierced with gun holes.
However strong, the walls of medieval Rhodes could not withstand the Ottoman artillery. An anachronic vestige of the Crusades, Rhodes finally fell in 1522 after a six-month siege carried out by Suleyman II, heading forces reportedly numbering 100,000 men. It subsequently came under Turkish and Italian rule. It was not until after the World War II, in 1947, that Rhodes and the rest of the Dodecanese islands were united with Greece.