Bari, Italy — AT Castel del Monte, the stage is set for tragedy or black magic. Clouds scuttle across the sky, and a milk-white full moon rises. Footsteps echo on cold, wheat-colored stone, startling pigeons into flight.
A medieval emperor hunted with falcons and cheetahs here, consulted astrologers and slept on Oriental silk.
Local people sought refuge during the plague, and brigands hid out in the castle. Vandals over the years stripped it, leaving little more than an empty shell on a lonely hilltop at the edge of the Murge, a barren-looking limestone plateau worlds apart from the sunny Italian south most people know.
This medieval masterpiece, begun in 1240 -- about the same time as Westminster Abbey -- has eight sides, linked by eight eight-sided towers.
Its seemingly endless repetition of the octagonal form has haunted mathematicians through the ages who see it as a work of pure geometry. The more mystically inclined impute occult significance to this temple of the octagon, noting that great buildings around the world, such as Jerusalem's 1,300-year-old Dome of the Rock, also have eight sides.
Whether icon or equation, the castle has more vibes than "The Da Vinci Code," as I discovered when I came here in February, drawn like iron shavings to a magnet. I didn't know why I had to see it, except I love a good mystery. And Castel del Monte is surely one, a model for the labyrinthine library in Umberto Eco's 1983 medieval whodunit, "The Name of the Rose." I stood in the castle's deserted courtyard at dusk, nerves taut, heart thumping, ears pitched, wishing the walls could talk.
But Castel del Monte, as silent as a sarcophagus and as strange as a UFO, keeps its secrets, glowing like the crown of its 13th century builder, Holy Roman Emperor Frederick II.
Like England's Richard the Lion-Hearted and saintly Louis IX of France, Frederick was one of the giants of the European Middle Ages, though far more complex than his contemporaries.
Cultured and brutal, despotic and enlightened, a Christian crusader who was excommunicated, he left a legacy that historians still debate, including David Abulafia, author of the recent biography "Frederick II: A Medieval Emperor," which seeks to demystify the medieval ruler.
But Frederick's enigmatic aura has proved hard to dislodge. In his time and afterward, he was called stupor mundi (the wonder of the world) and the Antichrist.
A 1927 biography of Frederick by German historian Ernst Kantorowicz was a favorite of Hitler, whose delusions of grandeur were fueled partly by the emperor's efforts to consolidate a realm that included Germany, the Netherlands, Austria, Poland, parts of France and Italy, Malta, Cyprus, Israel and Lebanon.
To oversee his vast domain, Frederick traveled widely and incessantly, taking with him his crown jewels and library, elephants, camels, hunting birds, bodyguards, poets who created the sonnet and mathematicians who gave Western civilization Arabic numerals.
Of all the lands he ruled, he loved low-lying Puglia best, in those days a richly forested region bordered on the east by the Adriatic Sea. Here he built his startling octagonal castle, part hunting lodge, part pleasure palace, part symbol of his might.
Among great architectural ciphers, Castel del Monte stands out for its stubborn unlock-ability, though it is less well known than others chiefly because it is in the relatively untrammeled, ill-reputed Mezzogiorno, at the heel of the Italian boot.
WARNINGS about the region's poverty and crime rang in my ears. I wore a money belt and resolved not to let my guard down, especially in Bari, the Puglian capital of 300,000, where I began my explorations.
I had planned to pick up a rental car and drive into the city, but I got cold feet on the plane from Rome, remembering an acquaintance who narrowly avoided a carjacking when she went astray in Bari. So I took a cab from the airport through the city's unlovely industrial outskirts and was safely deposited at the Palace Hotel, which occupies a modern high-rise close to the city's center.
My room's decor was so dated it looked as though Pat Nixon had conceived the design. But it lacked no amenities, and the front-desk clerk gave me good advice about where to eat dinner.
I had my first Mezzogiorno epiphany that night at La Pignata, around the corner from the hotel. It occupies an erstwhile Chinese restaurant but is now a temple of cucina povera, or "poor cuisine," which reflects the hearty peasant roots of southern Italian cooking.
I started with a seafood salad made of big, meaty langoustines, shrimp, squid, octopus and mussels in a simple olive oil and lemon sauce. Then I dipped into a plate of fresh, ear-shaped orecchiette pasta, coated in tomato basil sauce, a Puglian specialty, accompanied by a half-bottle of Castel del Monte red.