Geneve – street mosaic, originally uploaded by lullalli.

Vitreous Tile street mosaic detail –  Geneve, Switzerland

Mosaic Art Source mosaic definition:

Mosaic definition vitreous tile m.a.s.  vitreous tile

vitreous tile – square glass mosaic tiles most commonly 3/4″ x 3/4″ made in molds from glass paste. They have a smooth top but the bottom is keyed with ridges for better adhesion.   m.a.s.mosaic glossary