Continuing the drive up the Corso, a broad piazza suddenly opens on the right, flanked by the cathedral. The abruptness of the transition from between the dark lines of buildings into the sunlight of the square adds to the first strong impression produced by the beauty of the vast duomo. In its external architecture the church is unique: the charm of it to one who has been travelling through Italy is its utter dissimilarity to all the Italian churches. Architectural writers call it a building of the "Sicilian Gothic style;" and, though the expression does not convey a vivid image except to the student of art, any one can see its essential difference from the style of the North, and can recognize the rare grandeur and beauty of the church. The form is simple, but the dimensions are grand. Without the boldness of outline of true Gothic churches, the walls are so covered with ornaments of interlacing arches, cornices and arabesque slightly raised on the masonry as to produce an effect of wonderful richness. The style is peculiarly Sicilian, yet every observer of mediæval churches will at once detect the Norman, Italian and Saracenic influences blended in an exquisite harmony. Connected with the church by light arches, but separated from it by a street, stands the campanile, a mass of enormous solidity, terminating in many pinnacles and one slender and graceful tower rising above them all. Four other lofty towers, springing from the corners of the church, give additional lightness to its elegant design: they were added to the building nearly three centuries after the Norman conquest of Sicily, and yet their minaret-like form and pointed panel ornaments show how strong and lasting had been the influence of Arabian art upon the mediæval architects of Sicily. [Illustration: GROTTO OF SANTA ROSALIA.]