Palace of the Grand Masters (summer Mon 12:30-3pm, Tues-Fri 8:30am-9pm, winter Mon 12:30-3pm;Tues-Sun 8:30-3pm;6euros).was built over a temple of Helios (in Greek, 'Ilios'the Sun god); and some archaeologists believe that the famed Colossus stood here, overlooking the harbor. The Palace, completed in 1346, was modelled after the Pope's palace in Avignon, fourteen of the Grand Masters being French, and French being the official spoken language of the Knights' Order.
The underground storerooms of the Palace were intended as a place of refuge for the entire local population during enemy attacks or sieges. During Ottoman rule, the entire palace was used as a prison, even after the Gunpowder Explosion of 1856 when it was almost destroyed by an explosion of ammunition set off by lightning, and the first floor caved in. The Italians did the same but then rebuilt it as a summer home for Mussolini (at his command) and for Victor Emmanuel III (King of Italy and Albania, Emperor of Ethiopia). though neither of them, however, ever came to the island, the outbreak of war preventing them from enjoying its 158 rooms. The Italians laid Roman mosaics from Kos on the floors, and Renaissance furniture. They also put in a lift (elevator) and modern plumbing.
The inside is a bit of a Fascist fantasy of grand palaces with heavy furnishings and marble stairways and the like, though the outside is closer to the real thing, based on medieval engravings and accounts. On the ground floor is the Medieval Exhibit and Ancient Rhodes, 2400 Years , the first displaying fascinating trade items during the time that Christian Rhodes was a major trade center. There is a display of the sugar-refining industry which was an enterprise of the Knights and a Grand Master's gravestone, manuscripts and books, icons. The second floor deals with objects that reflect the daily life of the ancients. Exhibits are presented with information in both Greek and English.