Brionian Islands, a group of small islands, in the Adriatic Sea, off the west coast of Istria, from which they are separated by the narrow Canale di Fasana. They belong to Austria and are twelve in number. Up to a recent period they were chiefly noted for their quarries, which have been worked for centuries and have supplied material not only for the palaces and bridges of Venice and the whole Adriatic coast, but latterly for Vienna and Berlin also. As they command the entrance to the naval harbour of Pola, a strong fortress, "Fort Tegetthoff," has been erected on the largest of them (Brioni), together with minor fortifications on some of the others. The islands are inhabited by about 100 Italian quarrymen.