The ancient Amurianum became a real industrial area and soon also the capital of the world glass production. The glass art in Murano was jealously defended by very strict rules: the glassmakers had to keep the absolute secret on the techniques used and it was strictly forbidden to import foreign glass. In addition, this profession was protected by sanctions that prohibited those who were not registered in the art and those who wanted to move abroad imprisonment of their family members or even death.
Initially the production was of utilitarian character. Glasses, lamps, bottles and decorative objects were made mainly related to religious images, then, following the intensification of commercial contacts with the Middle East and becoming aware of the wise technology and sophistication of Syrian glass, the Murano craftsmen greatly perfected their technique to such an extent that in the fifteenth century. The manufacture of glass became one of the main activities of the Serenissima Republic.