We published a piece on the Knights of the Holy Sepulchre in Sicily back in 2007. Now a "cultural association" in Palermo, supported with public funds, is promoting a "Knights of the Holy Sepulchre Itinerary." That's their right and prerogative, but if you're considering their suggestions read Daniela Paglia's article first.
Why? Well, the fact is that the medieval Order of the Holy Sepulchre had only a very brief and limited presence in Sicily, and scarcely any in the city of Palermo. The Catholic order of knighthood bearing the same name is actually a re-foundation dating not to the Middle Ages - as is often claimed - but to 1847. It was only during the 20th century that the modern order got permission to use the Church of San Cataldo (a medieval structure), shown here with the red cross of the order visible in the apse window.
The focus of the "itinerary" being promoted in Palermo has nothing to do with the medieval Knights of the Holy Sepulchre, although a visit to the beautiful Norman-Arab Church of San Cataldo is highly recommended. Most of the points of interest along the way are associated with the Catholic Church and Sicily's Norman era, but not with the Crusades or the Holy Land. Not directly, at least.
I'm not condemning this entire "itinerary" a priori. I just wish that the people proposing it had done better historical research first.
That said, there are two very old, historic orders of knighthood represented in Palermo today having centuries-long continuity: the Order of Malta based in Rome (formally chartered in 1113) of which the Prince and Grand Master is Frà Matthew Festing, and the Constantinian Order of Saint George based in Naples (chartered in 1555) of which the Grand Master is Prince Carlo de Bourbon, Duke of Castro and Head of the House of the Two Sicilies, the dynasty that ruled Sicily from 1734 until 1860. The historical "home" of the Order of Malta is Holy Rosary Oratory (famous today for its painting by van Dyck) behind the apse of the Basilica of Saint Dominic, while that of the Constantinian Order is the Basilica of the Magione, a medieval church. Both of these churches are important stops along any "knights' itinerary" in Old Palermo.