Murano in Venice
Murano is a series of islands linked by bridges in the Venetian Lagoon. It is famous for its glass making, particularly lampworking.
Attractions on the island include the Church of Santa Maria e San Donato (known for its twelfth century Byzantine mosaic pavement and said to house the bones of the dragon slain by Saint Donatus, the Church of San Pietro with the chapel of the Ballarin family built in 1506 and artworks by Giovanni Bellini, and the Palazzo da Mula. Glass-related attractions include the many glassworks, some Medieval and most open to the public, and the Murano Glass Museum, housed in the large Palazzo Giustinian.
Half day should be ok to visit it, but you really can't miss this little beautiful island.