The basilica of San Nicolò l'Arena, attached to the Benedictine monastery on Piazza Dante, is the largest church in Sicily and one of the strangest. The vast bare facade was never finished, with squared protrusions where columns should have stood, giving the church the look of an enormous unfinished sketch.
Inside, the church is spare and white, almost austere by Sicilian baroque standards. The most striking feature is the meridian line set into the floor in 1841 — a brass strip running roughly north-south, with the signs of the zodiac at intervals along its length, used to determine local solar noon. A few clear days a year, a beam of light from a pinhole in the roof crosses it precisely.