The Venetian government, fearful the wood buildings that housed the high-heat furnaces of the glass factories would catch fire, and to protect the secrets of glassmaking, ordered the move. In the late thirteenth century, all glassmakers moved to the island of Murano. Venetian artists formed a glassmaking guild and new types of glass - aventurine (infused with metal oxides to form strands or specks of color), crackle and crystal, among others - were created. The textures and colors of smalti added layers of depth to the mosaic artwork.Дuring the Middle Ages, the popularity of mosaic art declined in most of Europe, but it continued to be popular in Italy, especially in Venice, where a mosaic art school was established. To create a lustrous finish, gold or silver leaf was pressed between two pieces of glass. The glass was made in small batches and poured onto a slab, causing uneven surfaces and hand cutting produced irregular edges. Metal oxides were added to glass to create numerous vibrant, deep colors. It was during this time that smalti was created. Mosaic art depicting religious subjects began to decorate churches, temples and even palaces. In the late fifth century, the fall of the Roman Empire brought rise to the Byzantine Empire and with it, a surge in Christianity. The ancient cities of Pompeii, Herculaneum and Stabiae - all popular resort towns for Roman aristocrats - provide excellent examples of various and beautiful mosaic designs. Figures, animals, plants and other objects were soon added, and began to appear more frequently as the focal point of the artwork, not only on floors, but also on walls. Mosaic art grew with the Roman Empire, and throughout Europe artists used tesserae to create variations of classic Roman geometric patterns, some interspersed with decorative panels, for floors. By the fourth century BC, smooth river rocks and smaller stones were decorating floors in the homes of Greek nobles, and by 200 BC, tesserae - small uniform pieces of stone and glass - were cut to fit closer together, adding more detail to the mosaic designs. In Turkey, in the eighth century BC, black and white pebbles were used to form designs in paved walkways. The first mosaic designs, dated to around 3000 BC, were cone-shaped terracotta pieces, imbedded - point first - into columns of the Stone Cone Temple in Mesopotamia. E' stato un vero e proprio percorso nel tempo che ha visto nascere e sviluppare il mosaico dalle sue prime forme fino alle piu' raffinate creazioni di oggi. La parola 'mosaico' e' ben nota a tutti, ma non tutti pero' conoscono la sua storia. Uno dei modi piu' antichi e conosciuti e' il mosaico. L'uomo ha da sempre cercato e scoperto modi per esprimere arte e creativita'.