The city of Rhodes with its castle and fortifications of the Knights of St. John captivated Gilbert. The Order of the Knights Hospitaller was established in Jerusalem in 1113 to provide a hospital (monks) and protection (knights) for Christian pilgrims traveling in the East. After they were ousted from the Holy Land, they eventually seized the island of Rhodes by 1309 and soon became the heirs of the Knights Templar after their violent dissolution in 1312. As the Moslem world expanded ever more closely from the East, the Hospitallers constructed castles on Rhodes and other nearby islands. The Knights, no less than their ancient Greek predecessors, chose to build their fortification walls as aesthetically pleasing as possible on the island of the sun god Helios. Using Rhodes as their naval base, the Knights harassed Turkish shipping, which regarded them as pirates. 

In the city of Rhodes, each nationality was called a Langue or Tongue which had its own inn or ‘auberge,’ and each was assigned a designated portion of the fortification walls around the city to maintain and defend. Inside the Collachion, the inner city, occupied by the Knights themselves, the Cathedral had been converted from Orthodox to Catholic in western style with Gothic arches. On the opposite side of the public square they built a very large Crusader hospital, which the Italians under Maiuri’s direction had converted into an archaeological museum by 1918. The main street led from the Cathedral and the Hospital up past the Inns of the various Tongues to the Palace of the Grand Master and the Knights’ own Church of St. John, the burial site of the Grand Masters themselves. Effigies of their worn faces and medieval robes can be seen on the sculpted stone lids of a few of their sarcophagi displayed in the museum. With its exotic mixture of palm trees, fortified harbours, and medieval buildings still inhabited by a cosmopolitan diversity of peoples, the city of Rhodes was unlike any place Gilbert had ever experienced. 

Since 1922 was exactly four centuries since the Knights finally abandoned Rhodes after a six month Turkish siege in 1522, Gilbert suggested he could give a public lecture to the Knights of St John in England later in 1922.