Fire-breathing is the unifying theme of Murano’s medieval church, with its astounding 12th-century gilded-glass apse mosaic of the Madonna made in Murano’s fornaci (furnaces) and the bones of a dragon hanging behind the altar. According to tradition, this beast was slayed by St Donatus of Arezzo, whose mortal remains also rest here. The other masterpiece here is underfoot: a Byzantine-style 12th-century mosaic pavement of waving geometric patterns, griffons, eagles and peacocks rendered in porphyry, serpentine and other precious stones.