The Grand Master's Palace was the fortress of the Knights of San Giovanni. In the two centuries in which they reigned over Rhodes, the island became the outpost of Christianity in the fight against the Islamic world. It was therefore a headquarters that if necessary could have housed the population, if for example it had been under attack. On either side of the entrance door two imposing twin towers. After the defeat with Suleiman the Magnificent, the Knights were expelled from the island and the structure became a prison. Around the middle of the 19th century, a powerful explosion destroyed a large part of the building and the reconstruction had to wait until the 1930s when the Italians had the mandate to modify the fortress in the residence of Vittorio Emanuele II and Benito Mussolini.