The word is palimpsest (or palinsesto in Italian). It refers to manuscripts written on velum, that when used over again, sometimes retained a ghost image of the original writings, much to the delight of scholars. In architecture, it has more to do with an edifice having multiple layers that show the evolution of an ancient building.
Palermo is a macrocosm of this idea, with layers of culture that pop up when one layer wears thin. The Norman kings are central to this cultural tapestry.
Ruggiero (Roger) I was the first Norman king to unite Sicily in the late 11th century. Roger practiced religious tolerance and allowed Greeks, Arabs, and Jews access to his court, so long as they were loyal to him. Religious tolerance was rare in a leader of the time. His son Roger II took the reins a few years later, and was a bit more ambitious, conquering Calabria and Apuglia, controlling the southern half of Italy. Still, he welcomed and encouraged foreigners in his court, having been raised by them in the court of his father. Arab mathematicians and geographers and Greeks teaching philosophy and rhetoric were common, as were English military advisors.
The tomb of Roger II, Duomo di Palermo.
The power of Roger II made the pope nervous, especially since at this point two men each claimed to be the pope. Roger played this masterfully, and became the most powerful man in southern Europe, even controlling a chunk of Northern Africa and as far east as Corinth.
Upon the death of Roger II, his son William (Guglielmo) I, a.k.a. William the Bad reigned long enough to make everyone hate him, then his son Guglielmo II (also known as William the Good) took over and patched things up, building the Catthedrals in Monreale and Cefalu'.
Anyway, the long-winded point is that a hundred years of religious tolerance left their mark. Little bits of Arabic pop up in the coolest places. Like churches that became mosques then became churches again. S. Cataldo (above) is unlike most churches, clearly, and it is in this church that there are mosaics of Roger II receiving his crown from the pope. Not a mosque, but it's hard to see it as anything but.
This window with obviously Arabesque tracework is on the Archbishop's Palace, hardly a bastion of Islam.
It also happens linguistically. Like the Italian word for artichoke, carciofo, coming from the Sicilian cacoccila, which comes from the Arabic word al-haršuf. It's linguistics, you have to use your imagination a bit.
Speaking of artichokes...my favorite thing to do in Palermo is to wander around in so-called sketchy neighborhoods, enjoying the smells and sounds of the marketplace. We were there during the peak of artichoke season, with bundles of 12 selling for a few Euro. This is the market where Ian and I split a tripe sandwich.
The Baroque facades on many buildings make Palermo seem oddly newer than it is. Many older buildings lost their faces to earthquakes and were rebuilt with the style of the day (which was baroque).
Still, my favorite parts of Palermo aren't the ornate facades of spectacular palazzi. It's the curved and crooked little medieval streets that make it almost impossible to navigate the old town without using church bells or bell towers to keep a point of reference.
Unlike northern Italy, there is not much public art, mostly because it was stolen. Not the mafia, but the numerous rapacious occupiers (the Spanish Aragonese and French Bourbons did a good amount of pillaging) who spent a good deal of time stripping almost everything of value from the island until Giuseppe Garibaldi kicked the Bourbons out. That which remains, however, is pretty sweet.
The Duomo of Palermo shows what happens when six or seven different architects work on a single building over several centuries. It's the ultimate architectural palimpsest, with elements of medieval, arabic, gothic and baroque all coexisting in a charming pastiche. It works.
Palermo's duomo I'll mostly give credit to Federico (Frederick) II, grandson of Roger II and the Holy Roman Emperor. He was an amazing man, called the stupor mundi, the wonder of the world, speaking at least five or six languages. He participated in one of the crusades (the sixth one, if memory serves) and was well-respected by foreign leaders, as were his grandfather and great-grandfather.
Anyway, Frederick got the same basic real estate we all get upon shuffling off the old mortal coil, his is just a little bit nicer than some. Still, he left some pretty things to look at.
HERE HE IS
THAT GREAT EMPEROR AND KING OF SICILY
FREDERICK II, DIED IN FIORENTINI, APULIA
DECEMBER IN THE YEAR 1250