Susan Spano / Los Angeles Times
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.
-- Susan Spano
Read more: In Italy, a riddle wrapped in stone
Pictured: Castel del Monte.